Your name reminds me of a pertinent story. When I was younger I had a midlife crisis. I bought a, then new, Dodge Viper. It was great for a guy who had recently been divorced. Until my kids moved in with me.
Anyhow, it had nothing nor could I order it with anything. It had a number of gauges. It had NO radio - it did not even have a slot to put in a radio nor did it have speaker slots to put speakers. Instead you listened to the engine. And it was beautiful. I paid much more attention to driving in that car than I paid in any other car (and I am a bit of a car buff as is evidenced by my many car stories - I always have a car analogy) and I think the reason for this was the car was just too damned much fun to not pay attention to driving and, secondly, there were no non-function related distractions in the car other than an occasional college chick.
The bad part is that it was my only car and the payments and insurance were pretty intense for that period of my life. I ended up selling it. I kind of wish I had it back again. The kids moved in with me, Daddy has the best toys, and I bought a 9-5 wagon. That car, not the wagon, and I had some great (and scary) times together.
Anyhow, I suspect it is not just HUD that is the problem but distraction that is the problem. You are paying attention when you are doing the Axl Rose Shuffle, on purpose, in a snow storm but you are not paying nearly as much attention when you are cruising down the highway and just passed your 600th mile of driving today. You are also likely paying less attention when you are playing some sort of simulation on a computer, regardless of what the researchers ask of you, because the penalty for failing to notice something is not nearly as high as it is when you are driving. Also, I tend to pay more attention when I am driving too fast or driving off-road. I live in the middle of nowhere so I can get away with it to some extent but I still am much more attentive and even tend to change my driving position before doing so.