It’s probably because as another commenter said not worth their time.
Seems like NYC has been battling this for years.
https://m.youtube.com/results?search_query=Fake+plates+new+y...
I vaguely remember some YouTube vlogger that would walk around and spot the fake/modified/obstructed plate. One obstruction was a leaf. That doesn’t even begin to include the probably illegal tinted covers.