Yeah, I think you question is a great one.
Now don't get me wrong about this I think they're great cars. But...
You're right, their owners don't signal for a lane change or turn. I just take it for granted that when there's a BMW on the road to be extra defensive. I also think your suggestion of a ergonomic design flaw is very possible! On the rare occasion that I'm outside of my own car and crossing a street (in LA) it's become something of a standard joke between my friends and I to say "watch out for that Beemer!" (- too many times we actually DO have to retreat back to the curb from a passing BMW!) Is it their attitude? Who knows?
It's become "So L.A."
Keep up the good observations!
by the way...will you pleez pick this as the best answer. &U Rock if u do! thin-Q vry mch!