I think the right to face your accuser is probably the biggest one.

As far as the lack of feedback goes, I can say having driven in Europe plenty of times that the cameras are extremely effective in getting drivers to obey the speed limits, but it's not the cameras themselves - the the knowledge thay they exist. Entering a 10km stretch of road that has signs posted everywhere saying "average speed zone next 10km" or something like that, where they snap a picture record the time of you entering the zone, then a picture and record of the time when you exit it and calculate your average speed. I've seen 5 lane wide roads full of cars just chugging along at 2km under the target posted speed. So for that I will say they are extremely effective at maintaining large numbers of cars at safe speeds.

Once the cameras have existed long enough, everyone knows they work, because everyone has gotten a ticket in the mail. That's when the posted signs of "camera ahead" really work. You've played the game before and lost, so every future opportunity will now have a giant red flag on it in each person's mind.