Inflation is driving up the costs, be sure to clip your coupons. I actually think most places are getting better, I remember when fast food restaurants were all extremely tacky looking, usually dirty and had nothing other then greasy processed garbage not that I cared as young child who had and still has a very limited food pallet to choose from. Its a bit better now, now a days Wendy's has real fresh cut fries for example and the ingredients across the board are have become slightly better, with some public and government pressure. In addition establishments like Mickey D's are going to great lengths clean up and renovate their buildings, one local one even have a fish tank, another other a fireplace! Maybe the locations in the USA haven't received the same love. Burger King is a notable chain that has fallen far behind though.
Remember its fast food, it is what it is. Dirty, Fast and Cheap as a T-shirt I once saw said.