I don't think your equation (elevator = turbolift) is correct.

Umm, that's what I tried to convey. The inequation elevator =/= turbolift is true, the equation elevator = turbolift is untrue. It's just that the inequality sign isn't easily typed in, but =/= was an attempt at that.
Or at least the turbolifts are their own thing in basically all episodes, even if one or at most two might let slip the expression "turboelevator" or somesuch. We could disregard that much like we disregard that "sickbay" gets called "dispensary" in one episode.
In any case, sorry about the confusion. And interesting that the signage isn't original.
Timo Saloniemi