One of the key aspects of digital currency is that it can be programmable. Because of this, each dollar could have a unique identifier. Think about when someone draws a picture on a dollar bill to see if it ever circulates back to them in the future. Now think of that at scale, using technology, with the government tracing it. Each digital dollar could have a unique code so that it can be traced as it circulates from person to person to business to business, giving the government a treasure trove of information about what you are doing, where you are doing it, and who you are doing it with.
