Your point on Hi-Vis Bob is very relevant and I do feel that it's value is limited when riding a bike. If I was a road worker or Police Officer standing on the road, then yes its value can't be argued against.That's all why I bought a white helmet the last time I needed one. But I am considering a colored helmet next time... exact same color as my bike. Don't know if that's a great idea but ... I do wear Hi-Viz gear otherwise and my cool weather gloves need replaced this year sometime and Hi-Viz gloves are on the short list.
And also that is the deal. Wearing the gear doesn't really eliminate all chance of injury or worse... BUT wearing the gear DOES very significantly reduce the bodily damages and not wearing the gear usually results in higher chances of more severe damages. Riding is dangerous enough without inviting worse injury by not doing all we can to reduce or eliminate at least some of the danger. Managing the risks is what it's all about.
From my own experience when they're asleep at the wheel they won't see or hear anything except there own little world. It doesn't matter how visible or noisy you are they just won't notice you.
My own experience is thus,
On hundreds of occasions driving bright white striped XJ6's, with all lights going and wailers blaring. We're talking headlamps modulating, Whelen grille and roof bars, Whelen noise, lots of it, and nothing, you could follow someone for a mile and they would just sit there oblivious at 100 mph + in the outside lane.
On a bike exactly the same, everything going, they wouldn't know if you were up'em. I got taken out by a driver in exactly this way, his response, "I didn't see you"....
Wear what colour helmet you want fella, because a white one will make no difference.
Upt'North.