Have not been to XXX for years, but have been to FatBurger - not impressed, never returned. Same with In-n-Out - thought the burgers were greasy, and, if I remember correctly, they only had American cheese. Yuk. At Red Robin and Kidd Valley you can get something besides American on the burger. And, as I mentioned, you can get a shake with real fruit in it.
In-n-Out does have real fruit in their shakes, but they are more traditional hamburgers.
You are likely just restaurant class and care more about what is on your burger than the burger itself.
There are some restaurants that have really good burgers, these tend to be the ones that use 100% sirloin and grind their own patties. Red Robin has these, so many these are the ones you are eating.
The best burger I had in my entire life was one that was prepared on a farm where the cow was slaughtered within 3 hrs of me eating it. It didn’t need any toppings, no spices, the meat was indescribable.