Maybe Chevron is the best, I don't know. But top tier is what it is... top tier gas. So it makes sense to lump it all together, just like the organization does. It's a standard they all meet and if anyone wants to go higher they can have at it. They don't have top tier A and top tier B if you get what I'm saying.
But I would certainly agree with SLCraig, in cars used regularly it doesn't seem to matter much. My OPE I have to dose on the side no matter what I use (with Techron quite often, actually).
Anyway, it doesn't seem misleading to me at all, if you meet a standard for top tier gas you're then selling top tier gas. Doesn't matter if Chevron gas is unicorn [censored] filtered through gold dust... the other products still pass the "top tier" standard without.