Ever noticed how fat wallets have grown these days? It is not because people have grown richer; it is because people are carrying plastic cards for all kinds of purposes. Typically there are several bank cards, a health care card, an identity card, a driver's licence, a club membership card, a retailer's discount card, etc. When credit cards were first introduced perhaps 35-40 years ago, they are touted to replace paper money. While the credit card has invaded everyone's pocket, the use of paper money is still as prevalent as ever. You cannot find a payment counter that doesn't also do cash transaction.
I try to keep my wallet as thin as possible by minimizing the number of plastic cards I carry. Even then, it is still too bulky for my liking. Working at the post office, I see people opening their wallets all the time. The typical wallet or purse is fat and crammed full of plastic cards. Every now and then, I'll see someone frantically pulling out one card after another as he or she tries to locate a card to make a payment at the counter. All is not lost yet... there's the smart card or digital wallet in the horizon which promises to integrate many cards into one.