“In the case of mislabeled food you are likely to find that the operation is Yakuza run.”
Even in Yelp?
But if the problem is a criminal organization like the mafia, passing a labeling law is hardly going to make much of an impression on them. That means that whoever tries to enforce it would be well advised to get some knee insurance.
I am not sure why fraud is something you think the government should not investigate.
One of the cornerstones of a free market society is that there are property laws that are strictly enforced by a just court system.