You're being downvoted, but I sort of agree...

How in the world can I stop worrying about errors like using a non existant class member and having a runtime exception? How can I refactor?

Ok, the core devs add annotations, then type hints to the language.

Some other people create MyPy, the JetBrains people use some other linting thing that does well, but does not match MyPy. The Pydantic appear and some other people says its awesome, but yet again, different to the others...

And all that to enforce things we already had 20 years ago in Java 1.0

How about using dynamic typing for small script and prototyping and using better tools for bigger projects?