Assuming a perfect system this still fails because you have now locked in all the law abiding citizens with someone who has proven they are ready to break the rules, effectively inventing a hostage situation out of thin air whereby a miscreant can terrorize their fellow passengers for the duration of the police response time.
The spiel is to do things you can get away with. You don't know if the other passengers are law abiding citizens. There is no way to tell how they respond when locked up with you.
I believe they don't keep the recordings for long if no arrests are made. It certainly seems like a good idea to not create data sets that are open for abuse later.
