For large purchases, cards are preferable, obviously, but for small purchases, why should I make it easy for my transactions to be tracked? Privacy, etc...
Sorry, you have no privacy.
Here is a wonderful blog entry by Scott Adams, the author of Dilbert.
The Privacy Illusion
It has come to my attention that many of my readers in the United States believe they have the right to privacy because of something in the Constitution. That is an unsupportable view. A more accurate view is that the government divides the details of your life into two categories:
1. Stuff they don't care about.
2. Stuff they can find out if they have a reason.
Keep in mind that the government already knows the following things about you:
1. Where you live
2. Your name
3. Your income
4. Your age
5. Your family members
6. Your social security number
7. Your maiden name
8. Where you were born
9. Criminal history of your family
10. Your own criminal record
11. Your driving record
12. Your ethnicity
13. Where you work and where you used to work
14. Where you live and where you used to live
15. Names of your family members
16. The value of your home now
17. The amount you paid for your home
18. The amount you owe on your home
19. Your grades in school
20. Your weight, height, eye color, and hair color
The government doesn't know your medical history. But your doctor does, and he'll give it to the government if they produce a warrant.
The government doesn't know your spending details. But your bank and your credit card company do. And the government can subpoena bank records anytime it cares enough to do so. The government can't always watch you pay for stuff with cash, but don't expect that to last. At some point in the next twenty years, physical currency will be eliminated in favor of digital transactions.
It goes on at length, read the rest here: