Is it legal under "European Union Law", or any law for that matter to charge for toilets in a restaurant?

I do not know but it makes sense to charge because I've only seen pay toilets in areas with heavy tourist action and or homeless people. Why should you pay more to eat at a restaurant or buy goods at a store because tourists and homeless people only go in there to use the toilet? Yes businesses are public places but they don't exist solely so people can use the restroom.