US carrier FAs do not do lavs. In fact, several times I've used the lavs just after FAs (AA, UA... they're all the same) and had to clean up after them. We're talking dirty sinks, wet floors, tissues on the counter. I always clean and shine up the lav after using it: Do unto others as you'd have them do unto you. On a recent SQ trip, can confirm that the FAs regularly clean and resupply the lavs- the toiletry drawers were always full of toothbrushes/paste; combs; and shaving kits, and I never walked into a dirty, smelly lav through four different 10-hour plus flights.