Writing in Computers & People back in September 1975, Paul Armer (from the Center for Advanced Study in the Behavioral Sciences at
Stanford) expressed some early concerns about the use of the payment system as a surveillance tool. In doing so, he made a very interesting point about the use of cash:
And further suppose that you have gotten into the habit of using the system because: one, it is convenient; and two, it may be cheaper than other payment mechanisms. Now comes an instance in which you want privacy and decide to use cash. If you have to obtain the cash from the EFT system, that cash transaction will stand out like a sore thumb. The point here is that it’s not enough just to have the option of using cash, the cash option must be used frequently or it becomes useless as a means for privacy.
I hadn’t really thought about this before, but it’s an important point. We can’t be that far away from assuming that anyone who pays in cash or Bitcoin at the local supermarket is a drug dealer or corrupt politician.