I shop at 4 major groceries here (large city, western Canada). All have cards, three give discounts or special offers to card holders including 5 cents off per liter of gasoline. The major bookstores also have cards, with discounts attached. I use two of them. That makes six cards. Add my 'phone company card, my Air Miles, two bank cards, credit cards (2), Library, Museum---and my wallet is crammed with 14 cards. There are others in a kitchen drawer.

When I take film for development, I give them my phone number and they give me a pick-up time. (My daughter, with a store, has all phone numbers on CD, with addresses and names, for everyone in the country with a phone- not tied to the country-wide cash register-computer terminals like the big boys- but the number gives her a name that she can check against personal identification).
I wish that all the concerns would get together so that I would have just ONE card rather than-
OH, YES, I FORGOT the government cards (Citizenship, Soc. Ins., Old Age, drivers license, car insurance, car registration, health plan, medical insurance-
Hell, I need a back pack!
Do I worry about privacy? No! It doesn't exist unless you have NO credit rating; if you have a bank account or a charge account, or have made time payments the data are available.
If I want your information, I pay a small fee.....