card.io is pretty cool—I wasn't aware of it until now.

I’m just shocked at how poor the security of the entire consumer finance system is, if you can accept payment just by taking a photo of someone’s card. I wouldn’t be surprised if professional credit card fraudsters had implemented this technology years ago (except with covert cameras).

A sincere question: what would stop you from photocopying someone’s card and using it to buy goods with this system? At least with Square you need a magnetic barcode, which might act as a very mild deterrent.

EDIT: FYI, I live in Europe, where we’ve had Chip & PIN-verified PoS transactions for a while now. Still not the best security, but at least it’s no longer trivial.