In my world, when it's warm, practically everyone gets naked as nature intended. Well, not completely naked, shoes and socks still have their uses, and accessories too, but... [Another shrug] There's no rule for or against any particular kind of clothing, it's just that being ashamed of having a body is something that happens to other worlds.

No reason it couldn't be cargo pants, just that most persons don't need that many pockets; everything important and portable is probably in one's handbag or other carry-all.