My idea is to have [optional] speed limiters. The generalized speed limits are very crude. Setting different speed for [small] parts of roads using signs has its limits. We attempt to fix dangerous spots by design, it is a wonderful art but not perfect. You can probably solve a lot of congestion by raising the maximum speed where it makes sense. It also allows for limited control over how many cars try to uses the same road. Traffic jams become bugs. It can log your speed on different roads, if there is a violation it can be treated like a bug too rather than a violation. If you don't have a limiter you can still move along with traffic. If there is a mark on the license plate it is not going to fast.