I guess partly because the Python tooling catastrophe makes it a quite a pain to set them up.
Salty huh
Saying you need to set up type hinting in Python shows that you're the one assuming it's a hassle like TS, where you need a different runtime to have access to something the language (JS) should have provided from the start.
Everything you need is provided by typing, which is included in a Python install. Just import it and start using it.