Which, knowing that drivers treat cyclists with less time and space than they should, is exactly this: WRONG.
Not knowing what a vehicle is causes drivers without any doubt to give more time and space than they otherwise would. A cyclist is the least dangerous thing to drivers, so as soon as you're identified you'll get lesser treatment than any other vehicle.
Lit up like a Christmas tree? Yes, with silly little bike lights and Hiviz:
"The best way not to be noticed is to wear urban camouflage - hi viz clothing, lots of lights and reflectors and a helmet." Dr. Tony Raven
I am a driver and a cyclist. The great majority of drivers treat me with plenty of time and space, to use your phrase.
The frequency of close passes, SMIDSYs and similar perpetrated against me seem reasonably evenly distributed between my motoring and cycling miles.
I am drawn to this idea that uncertainty causes drivers to give more space, but I've never seen it in action.
I am frequently driven by other motorists too, and have not witnessed this mindset you identify, where motorists somehow flip to their 'only a bicycle' default mode (once they've ascertained that the unidentified object is not a car, truck, tank or tractor) and give it less space.
As a keen cyclist, I find that I observe the way family, friends, colleagues and limo guys drive around bicycles. I simply do not see what you do and do not connect your observation with any argument for or against Hi-Viz.