They are loyal by nature. People have a loyalty coefficient, which you can discover, and use to your advantage. MBNA works through the managers of trade associations. Association members are loyal to their group. That loyalty can be extended to the group's card .
Loyalty applies to airlines.
I travel a lot speaking on Database Marketing. A few years ago, I realized that I should concentrate on one airline so as to achieve Gold status. I picked American, which required me to fly 25,000 miles in one year. January 1, the clock starts all over again, and you lose the Gold qualifying points you had built up the previous year. On Christmas day, I called American to see how many miles I had accumulated.