I didn't read through the entire thread, and there's no mandate for high visibility clothing in the US, but a couple of things leapt to mind. One of my work assignments puts me in a cockpit where I'm required to wear leather boots, long sleeve nomex flight suits, leather gloves, a helmet, etc. Certain pilots don't like it, in fact, many don't, because under the operating conditions, it gets extremely hot and uncomfortable. Some say it's a safety hazard because the extra clothing and gear only makes one hotter.
Personally, I wear it. I became convinced a long time ago, and I understand it's for protection. The life I save will be my own.
Some years ago an aircraft went down close to dark. Normally when one of our aircraft went down, one would assume all dead; survivors out of a crash under those circumstances just didn't ordinally exist. In this case, the aircraft crashed and burned. Later, it was learned that one crewmember did survive, got away from the wreckage, and propped himself up in a sitting position against a cactus. It was later estimated he survived three days before he died, and was found there. He was wearing a green nomex flight suit, and blended in with the terrain and with the cactus. The operator immediately switched to indian orange flight suits for no other reason than to make the crew more visible. Nobody complained.
A few years ago we went from yellow airplanes to white airplanes with red markings. Repainting the entire fleet got expensive. It was time consuming. Many of us felt the yellow colors were easier to see. However, we soon came to discover that the new paint scheme made a very big difference in out overhead support spotting us sooner, others picking us up faster, especially in smoke and low visibility. That white and red paint scheme wasn't a shot in the dark; it really works.
If high visibility jackets are mandated, who cares? In the western US at certain times of the year, every store carries racks of bright orange clothing as deer hunting season approaches. A decent high visibility vest can be had for a few bucks (dollars). I've kept one tucked in my gear for years. It may never be needed, but it may also make me easier to spot at a time, at some point, when it's wanted, and that's good enough.
Who cares what it looks like?? This is aviation. Not a fashion show.