Why don't male actors do nudity but actresses do? NSFW?

You always see tons of females on the screen topless or fully naked but you never see a man nude unless it’s just his butt. Not saying I want to see them nude but I was just wondering why. I know in Europe it is normal for men to do frontal nudity but here in America it isn’t. It’s like only the women get to be naked and men can’t unless it’s to laugh and be disgusted.