The bottom line point here is that if anybody who wanted to, could put a transmitter on any frequency they wanted to, the entire spectrum would be totally useless. It would be nothing but noisy chaos and of no use to anybody.
That fact was realized in this country early on, and was then made global through worldwide treaties that a majority of the nations of the world signed on to. That is why we have Canadian and Mexican clear frequencies on AM etc.
The object of these regulations is to protect the usefulness of the spectrum. When these criminals (felons in NJ and Florida) transmit on frequencies they don't have a license for it is a threat to the order and ultimate usefulness of the entire system. New York, New Jersey and Florida have passed state laws because the pirate problem is much more severe in those states than elsewhere in the country.
It is apparent that for some of these profitable pirate operations the FCC fines are merely a cost of doing business and far cheaper than an actual license would cost. So, there has to be an effective deterrent to stop them from damaging the system, or encouraging others to make things worse.
The objective is to make them stop transmitting and causing interference with licensed stations. It is apparent that the $10,000 fines don't scare them, but possibly a year or two in jail, and then being deported, if they are here illegally, might make them think twice.
There is a theory in criminology, made famous by former NYC mayor Rudy Giuliani, called the broken windows theory. Essentially it states the you have to pay attention to small things or they will get out of control and get much worse. Focusing on fixing those "broken windows" was credited with dropping the crime rate in NYC.
Most of these pirate stations serve immigrant communities, and letting those immigrants, legal or illegal, see members of their community get ahead by breaking US laws and running illegal broadcasting businesses is NOT the kind of message these new comers should be getting. In some urban areas the FM dial is full of these illegal operations.
Enforcement for local police doesn't have to involve any more than a couple of cops going with the FCC to arrest the criminals at the studios and transmitter sites. Even the most stretched police department has a responsibility to enforce whatever laws are being violated. The NYPD has about 38,000 officers, it certainly can find a few of them to spend a few hours to work with the FCC, arrest lawbreakers and prevent many radio spectrum "broken windows." Even the currently stretched Newark Police can spare a few officers for a few hours to do that.