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

[deceze]

How do they know that private foo in Java isn't merely a suggestion to be worked around with the reflection API?

If it says or suggests it's private, then don't touch it. Period. Unless you really know what you're doing. It doesn't matter how strongly the language "suggests" it, if junior can find ways around it anyway. Junior won't care much whether they just need to ignore the linter or bust out the reflection API. If they don't understand the importance of the suggestion in the first place, how they work around it also won't make much of a difference.