Why are Python's 'private' methods not actually private?

Question

Python gives us the ability to create \'private\' methods and variables within a class by prepending double underscores to the name, like this: __myPrivateMethod()

Answer 1

From http://www.faqs.org/docs/diveintopython/fileinfo_private.html

Strictly speaking, private methods are accessible outside their class, just not easily accessible. Nothing in Python is truly private; internally, the names of private methods and attributes are mangled and unmangled on the fly to make them seem inaccessible by their given names. You can access the __parse method of the MP3FileInfo class by the name _MP3FileInfo__parse. Acknowledge that this is interesting, then promise to never, ever do it in real code. Private methods are private for a reason, but like many other things in Python, their privateness is ultimately a matter of convention, not force.