Yes, we’ve read them say so here several times over the years.
No, many of are not. There are some Americans though (not a stereotype but true) who believe that there should be a top sheet between the guests and the duvet cover because the cover isn’t laundered as often as it should be. That being said, they may be confusing a duvet with whatever bedspreads are called in the USA. But whatever you call it, every item on the bed that has been in touch with flesh needs to be properly laundered at every turnover.