The only relevant guideline I found on parking citation data was that it is unlawful to look someone else up by their license plate. However, it is entirely possible for someone to do so without detection. My primary concerns, however, were ethical concerns - there were many people for whom you could determine their place of residence, place of work, and financial situation by their license plate's inclusion in these data sets.
Former HIPAA security officer here; to be abundandly clear, there _are_ very specific guidelines for which information must be anonymized.
I don't think you were saying the alternative, just sounded a little like "anything goes" which is definitely not the case.
As for your point about guidelines, that's entirely true - last time I read the section about encryption, it just specified "state of the art encryption" which is... a poor way to specify that.