I mean, decades of using one? And the mockery I received by men I got for washing my own hands? I have had family members and numerous classmates tell me that washing your hands is just admitting you peed on them.
Of course my experiences are anctedotal, but for me, it was a quite noticeable difference when I started using the ladies room. I'm not trying to make a definitive statement, absolutely there are men who do reguarly wash their hands, but there is also a very large majority of men who don't. From my experience, that's not the case with people in the women's room.