I think this is more of a cultural thing. Like, over here, it would be almost offensive to do a bbq with burgers, and we don't eat the meat on buns, but on a plate (or cutted into little pieces, eating it with a toothpick or a fork), usually with some salad or white rice, and of course beer. Burgers are sold merely at places like mcdonalds or burger king, kinda rare to find it anywhere else. There are frozen burgers you could fry up at home, but it's usually served at a lunch or dinner, never at a bbq itself.