And a lot of normies will call you stupid for caring because "everyone knows" and "it's always been that way". But I bet you if you conducted a poll or some kind of blind study where the participants are shown the ad, without the brand name, and then the product, almost no one would say the picture represents the product accurately for most of these fast food chains.

Not if you're selling whole burgers, but the "set dressings" are allowed to be fake.

You can use fake pancakes to advertise a syrup, and fake syrup to advertise pancakes. McD's can't use fake mayo on pictures of burgers, but you can use it in the "serving suggestion" picture if you're selling frozen burger patties.