They’re prudes where nudity is concerned.
Americans didn’t grow up with uncensored television, communal showers, and topless beaches. They weren’t raised on Renaissance art and stark realities. So, when an American travels abroad and encounters such things, he/she is typically shocked at what they’re seeing displayed so nonchalantly.
Eyes are covered, the channels are changed, and apologies are given. Bathing suits are worn to bathhouses and priceless works of art are giggled at. And chances are that is all done by an American.