The thing is, there doesn't seem to be a cheap and automatic way to (a) accurately filter out all incorrect tickets and (b) track the people down who were wrongfully ticketed. (Yes, analyzing the thousands of different parking spots where tickets were issued for their legality is an expensive process - and there's bound to be a very long tail.) So it seems pretty clear to me that attempting a proactive refund would be an expensive waste of money.
Yes, the police are responsible for doing their job right, and that's what they're doing now. It would sure feel great to punish some scapegoat in hindsight, but this is a classic case where it's difficult to pin the blame - remember, it was a systemic problem where one (small) subgroup of officers failed to be properly trained after a rules change.
People who have been wrongfully ticketed should contest the ticket, it's as simple as that.