I wouldn't discourage anyone from wearing hi-viz clothing, because I'm sure there are cases where a driver wouldn't have seen you except they noticed that weird color in their field of view. After all, it doesn't cost any more than a regular jacket, and if it saves your ass once, then it was worth looking like a traffic cone all the other times you rode.
But it's not a silver bullet. The real issue in the US is that it's so damn easy to get a driver's license, with almost zero actual training in how to drive. My home state allowed you to get a permit at 16; some states have even lower ages. You only had to have a licensed driver with you while you had your permit; as soon as you took your test and passed it, they issued your license. The driver's test consisted of driving around a closed course in a parking lot, stopping at a stop sign, doing a three point turn, and parallel parking. You never actually got out on the road. There's no mandatory training; the only thing close was Driver's Ed in high school, and a lot of those programs have been the victim of budget cuts. And once you have that license, the assumption is that you now know how to drive, and nothing could be further from reality. We treat driving so cavalierly in the US that it's about ten times more difficult (and expensive) to get a concealed carry permit or a hunting license, both of which statistically are far safer than the average teen behind the wheel. And far too many Americans are arrogant about their driving abilities; they don't think anything about eating while they're driving down the road, or screwing around with their smartphones, or just in general not paying attention to what should be their only task: driving. And there isn't a solution; some token training program about motorcycle awareness isn't going to suddenly turn a rabble of HUA drivers into cautious ones. It's one of the prices we have to pay for having a big country with big suburbs and a shitty mass transportation infrastructure; basically, you have to let just about anyone with a pulse have a driver's license, or else the system falls apart.
"No matter where you go, there you are."