And proving it in court is hard work, and probably low down the list of attack surfaces your average organized crime syndicate has. Plus criminals are perfectly capable of running moderately-successful businesses and just inflating takings, and genuine restaurant owners are perfectly capable of running places that are only ever full at peak times and with bookings (or are on their way to bankruptcy)

Yet this is merely presumed, stated as fact. You may be right, yet...

Right or wrong, such reasoning means that you and others wave away reporting. And without any indication anything is wrong, the police may never know, never investigate.

Thus, the abridgement of process means failure is guaranteed.

Proving it in court becomes easier if you have more reports from patrons.

What report? I went to this restaurant and it wasn't busy? That is not a report, that is just conjecture. If a DA went to a judge with that as the evidence for a warrant, they'd be insulted and embarrassed by the judge.

It’s just conjecture but if there’s already an ongoing investigation it could help.

You can report stuff to the FBI and they will ignore most of it.

The FBI really doesn't want your garbage reports about random restaurants unless there's actual evidence of a federal crime. They're overworked as it is.

Good luck trying to convict people of serious crime based on a handful of people testifying they visited a restaurant and it was empty!