Because men judge them every day.
Males are very visual, so that's what we focus on when it comes to women. Eyes, face, lips, tits, we need something to start wanting the woman, and it's usually some detail about her body. I mean we can all talk about choosing a partner for their character, bla bla bla, but if we don't find her attractive in some way, we can't have sex.
Males judge females wherever they go, and it's easy to be guilty of that, because your body does it all by itself. It's like an instinctive reaction to see if her hips are broad enough to bare children, and if her breasts are big enough to give enough milk. You need to watch and control your eyes in order to not look at a woman's body, that's just how it is (unless you have a serious lack of testosterone)
Women caught on to that, ofc. Being objectified for over 2 millenia