> Another incident was a truck mirror that grazed my helmet.

Of course, if you weren't wearing the helmet, the truck mirror may or may not have touched you at all.

This. I saw a bus mirror actually catch a guy's helmet and pick him up off his bike by his head, hauling him down the street.

Had he not been wearing a helmet, that never would have happened.

I hope you aren't saying that seriously. If those vehicles caught bicyclists in the helmet, they were both just too close to the cyclists. What if the cyclist swerved an inch to avoid a rock in the road, or even simply turned his/her head to look at something? Yeah, whamo.

Thus everyone should avoid helmets! They can kill. Seriously: Outliers do not describe a population.

So you are fine with approx an inch clearance with passing vehicles? I don't think so.