They aren't. Pretty sure if you're a vendor selling mail-order "adult" DVDs/BDs from major publishing houses, that's a business that you'll have no difficulty

They aren't. Pretty sure if you're a vendor selling mail-order "adult" DVDs/BDs from major publishing houses, that's a business that you'll have no difficulty running with credit card sales. Where you'll run into a problem is if you're a website that wants to charge subscriptions for access to loosely-sourced, user-generated content.