Not sure if this is helpful, but under the latest copy of Raspbian I was able to install RPi.GPIO directly from the main repositories using apt-get as follows:

sudo apt-get update
sudo apt-get -y install python-rpi.gpio

If you're running Python 3 (idle3 on the command line) instead of Python 2 (python on the command line) you need to install the RPi.GPIO library with this command instead:

sudo apt-get -y install python3-rpi.gpio

Well you have two options, either use python3 with

sudo apt install python3 -y
wget https://bootstrap.pypa.io/get-pip.py
sudo python3 get-pip.py

Or install it with python2:

wget https://bootstrap.pypa.io/pip/2.7/get-pip.py
sudo python get-pip.py

But if you just want to install pip you can do it with:

sudo apt install python3-pip -y

or

sudo apt install python-pip -y

You may install it with pip :

pip install RPi.GPIO

sudo apt-get install python3-pip

This should install pip3 for managing Python3 libraries. If you're using rasbian that is.
python-pip is for Python2 (as of 2019-09-09) if you need that too.

pip and python are two separate entities. There for installing one doesn't necessarily mean the other will be installed.

Some good documentation on the matter can be found at raspberrypi.org

And others have asked the same question on the official forums.

Just remember, most "safe" distro's tend to default to Python2 for their LTS platforms pre 2020. Meaning you will have to essentially add python3-<lib> (the 3 being the crucial element here) to all your installations. Otherwise you'll most likely get the Python2 equivilant of the library/tool for as long as Python2 is the default python environment in your distro. Like in this case.

Again, I'm using Arch Linux ARM for the most part, so I'm not to familiar with debian/ubuntu/etc distro's for the RPi platform. But that package should be called about the same as in Arch :)