I remember the days when movies shown on aircraft were edited for both content and dialogue.

These days, with so much content expected to be available at your fingertips, both in your seat and people bringing iPads on board loaded with R-rated streams, it's expected to be mindful of your neighbor on such things.

How that is distinctly "American" I don't quite understand.

Adult content does not necessarily mean pornography. It can include nudity, which Europeans are more comfortable with than Americans.