And all those systems were never deployed. Perception (f the banks, you can print money at home, and the money will grow in value over time) trumps research apparently.
There was, in fact, an effort to deploy those systems, during a period of time when the government was fighting as hard as possible to stop cryptography from "going mainstream." The efforts failed because:
1. David Chaum did not understand when he had won and kept trying to get more money for his startup.
2. There were (and still are) patents on the math that prevented these systems from just being deployed without waiting around for Chaum.
3. The security guarantees of digital cash are not nearly as important as people thought. It turns out most Internet users are not terribly concerned about privacy and banks are good enough at dealing with fraud that the benefit of digital cash does not outweigh the cost of deploying it.
You may argue that none of these apply to Bitcoin, and that is probably why Bitcoin has been so widely adopted. It remains to be seen if the economics of Bitcoin really work at scale or over long periods of time.
