[abalone]

Curve has its own card number. The closest thing to Curve here was a card called Wallaby. It somehow redirected charges from one card to another... I think they were getting creative with the processing rules and got shot down. Not sure how Curve does it exactly but I'm skeptical of their long term viability. Either they're similarly creative or they are acting like a merchant and recharging every transaction and eating some interchange. Maybe they get away with that more in Europe where interchange is low but it's still a net loss.

Anyway Plastc was about trying to actually emulate a card. All this has been leapfrogged by Apple and Samsung Pay.

[hocuspocus]

As far as I understand, Curve is viable due to the fact they issue corporate cards (you can see "for commercial use only" on their cards).

Europe has capped interchange fees to 0.2% and 0.3% for debit and credit cards respectively. However, three-party schemes (like Amex) and corporate cards are exempt and charge more. But you're right, I'm not sure how MasterCard is happy with that (since the product is clearly targeted at consumers).

[abalone]

I see, so they're charging merchants high corporate card interchange and then recharging the consumer card. Yeah, that's sketchy. I wonder if they're pocketing the difference.