I take your point Pops! To be honest, and no flannel, I often look at bike advice threads where you comment because you come across as having such a wealth of knowledge!
I have seen (no idea where they come from) convex cycle helmet mirrors. These fit onto your bike helmet and protrude to the front by an inch or so (like an insect antena). No idea how effective they are, but I'd imagine they wouldn't bounce around/vibrate as much as handlebar mounted ones may. Also no idea how they would be in an accident/fall where anything pointy near your head/eye isn't such a good idea!
I guess a mirror isn't, intrinsically, a bad idea. It's just no substitute for looking over your shoulder as that movement, in itself, also gives a driver a clue you're 'about to do or consider doing something'!