Many people in the Python community simply aren't writing those kinds of applications. They're writing applications where typing is not a benefit, it's a hindrance, so they don't use it, and Python makes that easy.
This is not to make the general claim "Typing is a hindrance in parsing applications", or anything close. It's saying "the current static type system(s) available in Python would have made this Python library much worse".
But often it can be helpful to know the shape of the input and the shape of the output. Eg are we working with a 2D,3D or ND array.
Before 3.11 it was not simple (possible?) To type this. But https://peps.python.org/pep-0646/ makes it possible. If somewhat clunky on the definition side.