The analogue version (if you will) of the loyalty card is the ubiquitous coffee shop stamp card. Here in Dublin, all of the coffee shop chains offer a card, which you can have stamped each time you purchase a hot beverage. Ten such stamps will earn you a free drink. I believe this situation obtains in a great many other cities.
Although this entirely off-line system doesn't aid the vendor in any way in terms of market research or profiling of customers, it is intended as a method of promoting customer loyalty in an overcrowded marketplace. The thinking is that, all other things being equal, a customer will choose your outlet over another, in the knowledge that they will be building up credit towards a freebie. In reality, the other outlet probably has its own loyalty card, so all things remain equal, and the customer is more likely to make their choice based on more traditional considerations such as taste and price.
I currently possess cards from six different chains, in various stages of completion. As a friend said to me on viewing said cards:
"I must question your loyalty"