[..] If this woman were to run down the street topless she would be arrested under indecency laws for showing her breasts [..]
That's not covered under indecency laws. One of the very broad "disturbing the peace" type laws, possibly, but not indecency laws.
Indecency laws require something much more seriously wrong in the eyes of the law and society, such as intentionally causing alarm or distress. Which, in practice, requires failing to cover your penis because only penises are seen as being bad.
Even then, it's not necessarily considered to be covered under indecency laws. Even that guy who's been jailed loads of times for rambling whilst naked hasn't been convicted under indecency laws but for breach of the peace and contempt of court.
It's true that the legal system isn't very flexible in immediately ignoring the legal situation when a prisoner says it's wrong, but your example is a bit wrong.