Perhaps you can comment about the bad habit of so many drivers following too close to the car in front of them. In order to combat this I have decided that, if I am unable to actually see the licence plate on the car following me in my rear view mirror, I activate my four way flashers. If the driver of the car following wakes up and backs off, not every time I must say, it might help those rear end crashes.
Like you, if someone is close enough to my back bumper that I am uneasy, I will turn on my hazard flashers, slow down slightly and move to the right edge of my lane. They generally pass me immediately and I would much rather have them in front of me where they are easier to monitor. More often than not they quickly pull ahead and no doubt find another driver to endanger leaving me to continue in relative safety.
I wonder that you did not raise the issue of those drivers who change into your lane in front of you leaving no margin for safety. Perhaps one could expect this behaviour if traffic was heavy, other drivers failed to leave sufficient room between vehicles and ignored your signal announcing a desire to move over. I often find it happening when the road is relatively unoccupied and there is no reason to move so soon.
Do you think that there is a driver out there who has not heard of the two second rule? They may even be aware that in some circumstances that three, four or more seconds are needed for safe following distance. The problem is in putting this knowledge into practice and realizing that if you don't, you are a bad driver.
I find if I just touch the brake it does the same thing and then I do not have to take hand and arm away from the wheel. Suppose it might be braking law, am I correct.
I can't see that you are doing anything incorrectly when you use this deterrent.
... if you simply adjusted your speed slightly, to gain more following distance, to compensate for the idiot behind you.
If the guy's an irritant, and there's nowhere that he can pass you legally and safely anyway, then turn on your hazard lights to tell him he's too close. But don't let him distract you from all the other stuff going on ahead.