I\'m coming from the Java world and reading Bruce Eckels\' Python 3 Patterns, Recipes and Idioms.
While reading about classes, it goes on to say that in Py
private and protected concepts are very important. But python - just a tool for prototyping and rapid development with restricted resources available for development, that is why some of protection levels are not so strict followed in python. You can use "__" in class member, it works properly, but looks not good enough - each access to such field contains these characters.
Also, you can noticed that python OOP concept is not perfect, smaltalk or ruby much closer to pure OOP concept. Even C# or Java are closer.
Python is very good tool. But it is simplified OOP language. Syntactically and conceptually simplified. The main goal of python existence is to bring to developers possibility to write easy readable code with high abstraction level in a very fast manner.