Originally Posted by slander
Obviously neither of you have used one.
That's a neat, albeit unsubstantiated and incorrect, assumption.
Having used one in just about every way you can (from changing tires, to maxing the jack out and driving off it to get tree unjammed out of my wheel well), this thing is dangerous as hell to use to change a tire on a highway and should be a last resort option. Its an inherently unstable tool by design and can easily kill you if your not careful. There's a lot of people new to wheeling and stuff on this site, and the hazards of using these things needs to be communicated. I learned the hard way on most of them (trying to unjam the highlift out from under your truck that fell on top of it is a PITA, or picking yourself up off the ground after the handle smacked you in the face sucks as well...)
Your assessment doesn't seem to be limited to on-road only.
Also - your assessment that it is a dangerous road side jack (as well as off road jack) is based on user error or incompetence. It has nothing to do with the tool itself.
You could put yourself in just a dangerous predicament with a bottle jack.
Also, having sliders helps when using the Hi Lift. I've removed/changed/rotated the tires on my truck dozens of times in my driveway or garage using the Hi Lift jack. Not once did I feel as though it was hazardous.