Eh well...

It's not always like that. Like in Canada, it is legal for women to show their chests, they just normally don't because they embrace traditional customs. Similarly, laws mandating shirts (such as in restaurants) are equally applied to men.

Actually, I would argue that in some cases, women have more freedom than men in this regard. I recall eating in a McDonalds where a woman was breastfeeding. Even if a man were not having some animal suckle at him, he would not be able to display them in a McDonalds without getting in trouble for it.

Similarly, if you look at standard fashions, women frequently wear lower-cut shirts or show more shoulder than men. It's like many of is instinctively recognize hypocrisy and attempt to level the playing field? That or we're all just fat.