Agreed.
If a policy requires nearly perfect implementation, and follow through, and good behavior of the people, in order to succeed, and you rarely achieve / sustain the follow through by the community or police, etc. then it is not a good policy. Even though the concept was nice.
A policy is everything, start to finish. You can't just say a policy was good except for the implementation. No matter how good it makes you feel that you got the idea right, it just wasn't carried out the way you thought.
Sure, maybe? But maybe it's just a bad policy? Maybe we could adjust the implementation? Maybe we can look at other places were things are better?
Maybe a bit of shame could be helpful, too. SF and Portland have turned into a national punch line. That's shameful.