In Europe actually most manufacturers quit making single pole switches and sell 3-ways for everything (and those that still do have such a negligible price difference that most electricians and retailers only stock 3-ways any more).
Years ago I remember reading somewhere on these forums though, that a 3-way is not UL listed for use as a single pole switch and thus illegal, posing a shock hazard since the unused traveler terminal becomes hot in the "off" position of the switch... on the other hand I assume anyone removing a switch cover should know enough about wiring not to touch any terminals without killing power to the circuit. I guess that's one of the classic "lawyers vs. common sense" cases
