then why do burgers, fries and pizza suck at high en places?
Even the relatively modest price difference between a place like McDonald's and Five Guys makes a drastically different burger. There's a restaurant we go to here in NYC semi-frequently called Balthazar which is "affordable upscale", and they are far-and-away my favorite burger in the city and they serve pomme frites style fries, which are delicious.
I don't generally order food like burgers when at a higher end restaurants, but the difference between a higher end version and a more economical version probably isn't that pronounced because the burger is a humble food by nature. When talking about foods like fish and steak or dishes that are labor intensive, forget it. It's not even worth debating.