I understand your concerns, but if we don’t require clothes to cover our butts, we have public nudity.
I can see where gov’t shouldn’t have to declare WHAT covers your butt. boxers, pants, skirt, whatever.
There isn’t nudity in this tacky style, the point I think is to show off the boxers (brand?). The funny thing is, this style has been fading out a lot, but if it becomes illegal, it may surge again as a sign of rebellion.