I think of a little maze for the rats to find the cheddar, which they endlessly repeat just to get more meaningless rewards while never being able to escape the

I think of a little maze for the rats to find the cheddar, which they endlessly repeat just to get more meaningless rewards while never being able to escape the maze. What you describe sounds more like a hamster wheel. Do rats also run on such wheels? In any case, IMO the streets of SF make a good visual for the OP's definition of rat race.