RP Prepaid cards

I think that RP prepaid cards should be redeemable in any server no matter where they were purchased. It makes sense for the people who live in another region to be able to do this as credit card details aren't the most fun thing to hand out. Some people just don't feel safe doing it. To make more money riot please make RP prepaid cards redeemable all the same for every server. I would be spending much more money on league if this was possible. Thanks