Protected classes are just one of many examples. There are many others.
Search for "mortmain" for one that's been around in English common law since the Middle Ages. Then search for "takings clause" for one that's been around since the U.S. Constitution was enacted.
If the government forbids them from starting a cafeteria in a space where that was formerly allowed, that is a "taking". The government may (or may not, depending on the court) be able to do this, but if they do they are required to pay the landowner for the lost value.