Consumer credit has been around a long time; it's part of what drove the boom in the 1920s. And loan sharks are even older -- the difference with credit cards is that their interest rates are lower, and that you can efficiently borrow in smaller increments.
Consumer credit was very popular in the 20s and then fell out of favor for a long time, from the 30s all the way up through the 1970s. Possibly because people discovered what a terrible idea it was in 1929. ;-)
I've been talking with my parents about this lately - up until the late 1960s, people almost never bought stuff on credit. If you didn't have money for a car, you walked or took public transportation until you could save up for it. You waited to buy the latest consumer gadgets, you didn't pay them off later. If you couldn't afford the down-payment on a house (which was nearly always 20%, non-negotiable), you rented until you could.
I was born in the early 1980s, and my first money lessons were always "Save up for what you want - you can't buy stuff you can't afford, regardless of whether anyone says you can." I suspect that my generation and the tail of Gen-X was roughly when that changed; nowadays, it seems like kids are being taught "Okay, you can have it, just charge it to plastic."
