You're quite right there. It's not possible to know what a single driver does with his vehicle on average. But from my experience (the following figures are simplified):
For every 100 SUV encounteres, I see maybe 1 being used to it's potential (i.e. the use is 'justified'). This is everyday.
I can then conclude that 98%* of SUV trips do not require an SUV to do.
So if (and give me this assumption for now) SUV endanger others, or hinder their driving, wouldn't it be logical for people to be annoyed at "all those SUV" drivers? The main point is, that SUV-trips are largely unnecessary, so their effect on the rest of traffic is also largely unnecessary. And because of the quite large percentage of unnecessary* SUV trips, people get annoyed with them in general.
(Compare this with cab drivers: there are many taxi drivers that are pushy, annoying and arrogant. They annoy me. But the percentage of annoying taxi drivers is not high enough for me to consider all taxi drivers annoying until proven innocent)
Finally, I honestly do believe that more than 75% of the SUV drivers around here
never use the car for something that requires an SUV. They consider it a status symbol and only want a bigger car than their neighbour. The huge popularity of luxury SUV's supports this notion.
I'll admit though, that jealousy can be a 'helpful' factor in the SUV generalization, but it is not the root cause.
* say, 1% of the trips is SUV-potential, + the return trip leaves 98% of the trips not requiring the use of an SUV.
**unnecessary trips are of course as perceived by other drivers.
I've left the actual "do SUV's endanger or hinder traffic" discussion out of this post. But you're point regarding the small cars and motorcycles, I agree: there are certain classes of drivers that are just as dangerous or more than the average SUV driver. Please don't get me started on that! I'm can't always keep my cool when discussing wreckless drivers. (SUV, truck, motorcycle or otherwise)
When I see a stuntdriver on the road, I sometimes silently (or not so silently) encourage him to drive of a cliff. And I keep getting the song "If I had a rocket launcher" in my head. No idea where that thought was going
