If you have previous/other manually installed (= not installed via pip) version of OpenCV installed (e.g. cv2 module in the root of Python's site-packages), remove it before installation to avoid ...

Thus the opencv-python package could maintain backwards compatibility by simply being a meta package that requires opencv-python-base and opencv-python-graphics. I'm not sure if this is easy / ...

As we all know python has its own package manager called pip which can be used to easily add libraries for the python. And yes there is also a way to use PIP to install openCV within minutes on Pi, ...