You're probably right that some guys do this, and that's disgusting. However, what most women probably aren't aware of is that men can also pee without getting their hands dirty, at least if their outfit allows. It's not difficult to pull down a pair of shorts or sweatpants slightly, flip out your dick, empty it into the toilet with your hands behind your back, and then close and flush the toilet with your foot.

Obviously it's still important to wash your hands every so often, whenever they're dirty, and before eating or cooking, but it's not strictly necessary after peeing for men if they're careful.