Interestingly enough it's often the industry in question often arguing for limits on itself. Less supply means they get to jack up their prices.
Don't get me wrong; there's plenty of room for "decent Mexican places," but if too many of them open, then they might all end up with not enough customers to survive. Limiting the number of restaurants means that there will be enough customers for most of them.
Too bad. That's not the business of government, its the effect of market. They may all go out of business if people stop liking Mexican. Government shouldn't be picking winners that's the people's business.
Limiting the number of restaurants means that there will be enough customers for most of them."
There's no such thing as 'keeping competition down to reasonable levels.' That's why we have a market. The optimal supply of restaurants and customers should be determined by the market, not government or protectionist incumbents. Unless you can make a legitimate case that allowing more food trucks, restaurants, or whatever else harms the health or security of society, there is zero reason to limit their numbers.