Large fast food chains: Why is there no law against this?

You know, the large burger chains, the advertising pictures of their burgers look oh so good but the product comes out looking like a pathetic, shrunken, flat, half cold, pathetic looking thing with a wilting piece of lettuce stuck on top. How do the big burger chains get away with this? Surely it's false advertising and I bet a small business would get punished for it.