I've seen boys dress coded for shorts being too short. Very few boys will dress in short-shorts, but if they do, they should have the same requirements as girls.
I've never seen a boy wear spaghetti straps or a crop-top (except some of the football players at practice with their cutoff t-shirts). If they did, I would expect them to be dress-coded.
Our district also doesn't care about earrings or long hair on either gender.
I agree with you that we are much more focused on girls' dress than boys', but I think that's more an issue with fashion than school boards.