Gas Broke $5 a Gallon!

[Silence]

In that sense, even taxi is ambiguous. Airplanes taxi down runways. "Cab" is more specific.

That said, you do have a point. The ambiguity rarely comes up (and if a customer asked for gaseous "gas" at a store, he's not really addressing what type he wants anyway), but it can cause problems. Natural languages often, though.

[cantab]

Yes. Taxi is ambiguous. So is cab. If a trucker says "It's in the cab", and a taxi driver says the same thing, the meaning of cab is different.