It's not quite all or nothing, but it's annoying to work with it if you only use it for some things and not for others. I find that if you have a mixture of TS and JS in various files I would rather just go all in on TypeScript so I don't have to manually annotate.
With Python you're still just working with Python files.
But they both seem to handle typing similarly.
I can't put my finger on why. Anybody else?