A bow and return for a clap used to be standard on EVA air (the Taiwanese airline) whilst taxiing to the gate. It was discontinued a while back - apparently because it interfered with the crew's preparation for disembarkation. My theory is that they (the airline, not the crew) just felt to arrogant to continue with the practice.

Is it really universal on US airlines? Hasn't been when I've flown with them.