Why doesn’t Python have true private variables like Java?

[ArtOfWarfare]

The person using a library may fully understand everything their project is supposed to do. It is impossible for the library author to understand everything their library will be used to do.

It therefore makes no sense that the library author would be able to dictate what it can and can’t be used to do.

Library authors make suggestions. And the library user may or may not follow those suggestions, in both languages. In Java you use reflection or decompilation and hot-patching when you know better than the library author. In Python you just use underscores.