The products are not equal. The thickness of the product is often determined by what material it's made out of. Glue downs (dry back) are often 2-5mm thick with 2.5/3/4.5/5mm usually being used for the nice products on the market. The rigid core products are usually 3.2-5mm thick (measurement without pad) this isn't SPC it's just rigid vinyl not as many on the market anymore, usually didn't come with a pad attached often cheap products. SPC/ESPC or effectively different variations of plastics often vinyl mixed with dehydrated calcium carbonate. Usually 3-6.5mm thick when not taking into consideration the pad, the pad options are generally EVA/IXPE/PE/Cork. EVA is the cheapest but is also one of the stiffer products usually seen on the thinner products as it help limit vertical deflection of the plank when being walked on usually it doesn't like having glue on in, does poorly with glue assist installs, has a distinct smell like the EVA foam used in kids crafts passes air quality tests so who knows. IXPE and PE usually has a glossy feel, has some of the best sound mitigation second most expensive, often advertised as "antimicrobial" technically true functionally worthless IMO, but it looks good in marketing. Cork is the natural, best at glue assist, will react with water and swell, dense, middle on the sound, usually on the higher end products. This section of LVP/T is the most common product and can go from junk to awesome. Usually the 4mm thick product (non including pad) is the standard for solid products, Tarkett Progen, Coretec Pro Plus, Provenza Concord Oak are well known solid performers. MSI Andover and Cyrus, Happy Feet Maverick, Southwind Rigid Plus and a bunch of others are examples of some more price conscious options. Many people caution using products below 5MM thick (4mm with 1mm pad) because it can introduce a lot of products who's only real selling point is price. The companies importing them may or may not be testing and let the customers complaints let them know something is wrong. Also the low prices often attract customer without means and customers trying to be cheap, it's more likely these groups of people will not prep the floors correctly and these products have very little margin for error when the are 3-3.5mm (again not including pad) so they fail. It may be the products fault it may not be, but the installs are often poor quality which doesn't help anything. Exception for brands that fall in the below 5mm (4mm core) are Karndean click, Mannington, Shaw's Floorte Endura 5 (these lists are not exhaustive trying to list names people may run across there are others, but I cannot spend all night making sure of sizes and a million skus out there). In this group there is the largest chance to run into a problem because it's such a large section of the market. The next is the WPC style product the foamed vinyl and there is one with charcoal using PET. These are usually 5-10mm thick or thicker before pads. More likely to have Cork as a pad. Most common thickness is 8mm, 7mm core 1mm pad may also come with 6.5mm core and 1.5mm pad. Generally considered to "feel" the best underfoot. Have the best registering, embossing and visuals. Do not like lots of exterior sun, expand and contract more than SPC. Most labor to produce and most steps from material to end product. I don't believe there is any production in the North America think there may be one in Europe and the majority is SE Asia. Big names is Coretec, Mannington Adura, Provenza, Shaw Paragon HD. Often the customers buying them often will pay the most for prep and rarely have issues, these higher end products are often tested more than the budget products as there is more money to do so and some of these companies spend a lot on advertising so they are not focusing on being the lowest costs. Wear layers expressed in Mils (.001 inches or thousandths of an inch). Thicker is usually more "durable" than thinner. It does not mean that it's more scratch resistant. A 20 is not more scratch resistant than a 12 by default. The test often used are the Tabor test and castor chair test. This is rolling abrasion with fix "grit" and measured in cycles, the manufacture uses this to set the expectation of durability. They are often made up of multiple layers of material, so the the thicker products often have more things in them, 20 mils can often have UV protection/coatings or hydrophobic/philic, that the thinner often do not get so they "perform" better. But you have to know what you are comparing, this part sucks because there is not data table to look at, there are dozens to hundreds of advertise wear layers and the majority aren't made by the "manufacture" anyway so the RSA in a store cannot be sure if two brands aren't using the same thing. Take Shaw endura 5, sold as fortitude if you buy it from a retail store the package will say ceramic micro bead but if you look at a Fortitude card it will say exoguard, the boxes are the same they come in with the skus for both products on them. The RSA, retailer and even the manufactures sales reps have no clue what is on the products other than what is advertised. There are differences in quality, but giving a solid comparison is really really hard. Also most all metal household items, some plastics like ABS, Aluminum, rocks, sand, glass, many things in the house are harder than the best wear layer on the market they WILL scratch the surface. walking on the floor of a 6 mil wear layers is unlikely with socks or slippers on wear through in 10-15years of use, 20mil not going to happen without assistance. The issue with 12 and 20 is that customers may see no difference residentially in "wear", but you will really never see an HD/7 screed/ EIR (embossed in register) visual/texture in a 12. For the same reason you won't run into a 7 series BMW with cloth seats. There are tests being talked about for products to establish a better comparison, usually by the higher end companies because they want to advertise how much cooler they are. The wear layers usually are a clear vinyl/urethane with an aggregate component, ceramic micro bead (think glass beads) Shaw's exoguard is an example, Aluminum oxide (Mannington has a patent or patens supposedly on the rights for a version that has better particle dispersion and is often considered "the best" aluminum oxide finish). Then there is the Diamond/Quartz options like Armstrong D10 Shaw's Exoguard+ are examples. There are also finishes that use a vapor deposition finish like Ihause Sono Eclipse, Next Floor Scratchmaster that don't use a film, these finishes are often very hard and are often compared to being 20mil layers, but are not the same. Those products may have demonstrations with grill brushes or chore boy scrubbers, but remember that's not what your doing in your house, if you take any other metal object you'll get shut down, "oh well it can't handle that" oh so it can handle a ridiculous scenario. The issue is you use the same saw or utility knife to cut all of them. The utility knife with the cheapest steel that can be hardened to cut carboard sold in boxes of 100pcs. Take a thumbtack to them, it will scratch, drop a cheap pair of scissors tips down, they will all indent, spc,wpc, they all get damaged from that kind of action. There are differences, but there are some similarities, because there are universal actions that will damage everything that are far more likely than someone walking through the wear layer. Rolling anything being one of the worst offenders. Locking mechanisms are very important, quick rundown is that in lab testing they all work fine. The angle angle systems seem to have more wiggle room for error than the drop locks (except the mechanical drop locks like the Valinge 5G). Unilin and Valinge 2G are exampls of angle angle. I don't dislike drop locks, they can be installed faster and it's "easier" for consumers to do it themselves. The mechanical side locks like Valinge 5G are excellent, but are only seen on the higher end products it's a significant expense. The drop lock from unilin with the white plastic tab which Mohawk was the only one that used it was incredibly unforgiving on unflat floors, but on flat floors holds up great. Locking mechanisms is very important, but hard to describe in print. There are also proprietary locking systems like on Inhaus Sono, there are others I saw at Surfaces but I cannot remember. Any company I left off (most of them) is because I would have to actually look up data on it. HD/Lowes/Floor & Decor, Menards I don't know enough about every product, there are thousands of brands and rebrands. So this is not an endorsement or by extension a tacit dislike of products not mentioned, just some framework for the products. Hope you find some of this helpful. There is a lot more to it than that store experience you mentioned. If clarity is needed i can do that.