I don't know whether this story is real or not, but I've worked for several restaurant owners who would absolutely do this. They would not only do it, they would brag non-stop to anyone who would listen about how clever they were to come up with the idea. There are unfortunately a lot of business owners out there for whom the only thing they like more than making money is making money by directly screwing someone over. It's the only thing that makes them feel smart. I've had the misfortune of working for a few of them.

If this isn't a thing now, I guarantee someone is going to try it.