Yeah pretty much this. I am sure this happens because of laziness on restaurants' parts - it's easier to lump all this similar stuff together under "BURGERS" than have a seperate section which doesn't quite fit anything.
If I do have a chicken breast burger though, I am 100% aware that it is chicken breast (maybe) and not a burger and would not refer to it as such outwith the burger buns, while I can have a beef burger without the bun and still call it a burger.