I had several legitimate businesses ask me for that. Thankfully they were fine with obscuring all but the last 4 digits of the card.

I don't get why they do it though. Faking a card photo is trivial so anyone trying to defraud them will just do so. These guys can manufacture physical replicas of cards to cash them out at ATMs, do the companies really think they won't be capable of altering a picture?

I'm assuming someone somewhere told them to do it and nobody took a minute to actually look into it deeper and realise how easy it is to exploit (and thus useless at preventing fraud).