You realize that all drivers should be prepared to approach a bicycle going 5 kph, right?
If you can’t slow down safely when you come up behind a slow vehicle, then you’re driving too fast and should probably have your license taken away.
I’m not concerned about myself not being able to stop. I’m generally not concerned about my behavior. I’m concerned, once again, about how OTHER drivers will react to ME going slowly and becoming an obstacle. I can control myself, I can leave proper follow distance. I CANNOT make anyone else do that. No one can, all we can do is encourage better behavior.
If we follow that thread, how do we encourage people to slow down? We can do so with fines and enforcement. We can fine anyone who goes over an arbitrary speed. Or, we can do it with physics and behavioral psychology. Make it so that those same roads are less easy/fun/convenient to drive on at high speeds.
I’m beginning to doubt that you’ve read half of what I’ve posted, so I’m not going to continue with this.
Usually what I do is swirve a lot to the left on my bicycle as soon as I see a car coming behind in the rear view. Its very effective in slowing drivers down.