(sigh). You're choosing not to see my point. I will extend the olive branch and come to your corner: yes, people hauling big rigs have traditionally not been able to see "through" the rig. You are correct.
And yes, I get the fish-eye argument. But it sounds like an inconvenience, rather than an impairment.
But if we come back to my question...
Lets say I'm driving a small vehicle, not towing anything.... bear with me, I'm using this different example as a way to illustrate my point... There is a rearview mirror. Am I taking my eyes off the road where they should be when I glance at that mirror? Possible answers: Yes, if done at inappropriate moments. Maybe... if done at in appropriate moments.... NO however, if used appropriately. Well, I don't think our opposing views (pun intended) will be settled conclusively. To each his own. Thanks for your interest in my question though, I sincerely appreciate it.
Here's an example of knowing what's close behind you might affect your decision making: You see something ahead on the road which could be a small animal... like a squirrel, or a gopher... If I know my surroundings, I may elect to brake a little heavier than I otherwise would if I know someone is tailgating me.... I don't want to intentionally harm any living creature. Not recklessly heavy braking mind you, well in control; however, knowing that someone is right on top of me behind me, 1. My senses will be heightened, 2. I'll brake but probably more slowly, more cautiously, and 3. Given the choice between slowing considerably or just reducing speed and going over the little fella to avoid getting rear ended.... sorry little guy, them's the brakes! (another pun intended). So yes, the better you know your surroundings the better off you'll be. Hence I'm interested in a camera behind me.
I also appreciate that I've travelled enough to know that this might be a total foreign idea to people who have only ever travelled on busy interstates because there is ALWAYS someone behind you. But often there are times when you may be on less traficked roads and have such luxuries.