It's fairly common in the USA to have 480 phase to phase, and 277 from one phase to a neutral. There's usually a stepdown transformer to provide some 120/208 but then again, many things CAN run off 277/480. In commercial buildings that is.
Incorrect.
In the US, 480V service is called "heavy power" and usually only available to industrial areas and large commercial developments. In large buildings it runs HVAC and is distributed throughout buildings to feed local 120/208V transformers.
The only common use for the direct 277V phase-to-neutral is for lighting fixtures designed to accept the high line. The 3-phase of course supplies large 3-phase loads. For all virtually all other '200V' devices, they top out at a maximum input of 240V and WILL quickly fail when fed anything over 250V.