Getting out of your car when pulled over or at the border seems like such a big deal in the US, it sure as hell doesn't in most European countries.
It has always baffled me that it is that way in the US (I'm from Germany). My sister was once yelled at - at gun point! - to get back in the car when she got pulled over near Detroit for speeding once.
Whenever I get pulled over (rarely, so far mostly routine inspections, and one 10km/h speeding ticket), my first instinct is to actually get out of the car because it's impolite in my eyes not to. I had my car and baggage searched at the Czech border once and we were of course standing around the car while the officers were looking through our bags, glove compartment, etc.
I suppose I need to keep my instincts suppressed on my upcoming trips to the US, though I don't plan on getting pulled over in the first place. :)