The cheese goes on top because if you just put cheese on the patty or patty on the cheese when assembling the burger, the cheese won't melt enough. You have to let the cheese sit on the patty while finishing cooking the patty so the cheese will melt into and around the patty. Obviously putting the cheese on the grill then the patty on the cheese won't work, so the cheese has to go on top or you get cold, only partially melted cheese. Blech.
The cheese goes on top because if you just put cheese on the patty or patty on the cheese when assembling the burger, the cheese won't melt enough. You have to let the cheese sit on the patty while finishing cooking the patty so the cheese will melt into and around the patty. Obviously putting the cheese on the grill then the patty on the cheese won't work, so the cheese has to go on top or you get cold, only partially melted cheese. Blech.