not because they don't want to or because it's to slow

but because it's not really viable without fully executing module loading in a sandbox, which might seem viable until you realize that you still need to type check `__main__` modules etc. and that its a common trend in python to do configs by loading python modules and grabbing the module locals as keys of the config or loading some things might actually idk. initialize a GPU driver :sob: So it's kinda 100% guaranteed not possible to do fully correct type checking for all project :smh:

But also python is one of the slowest popular languages (and with a large margin to any not also "one of slowest" languages). Only by moving hot code into C++/Rust is it fast, which often is good enough, but a type checker is exactly this kind of software where this approach stops working.