Correct in general but there are exceptions. At BitPanda, you'll get more of about 5% fee than 10% despite the use of a card, alas only EUR denomination
But the real issue lies elsewhere, on the characteristics of the prepaid cards which are rejected most everywhere

An app @ LBC ? There, I am indeed concerned about the escrow quality. Cards are a very picky kind of item where it's easy to claim codes are invalid, or the card credit is empty, etc. + lots of scammers so like walking on a field of land mines ?

Thanks for the brainstorming anyway