To be a little optimistic, it does seem to me that the ESTA system (where an electronic check is done for visitors looking to use the visa waiver program before they travel) has greatly reduced these types of situations. However, ESTA is only used for visitors arriving by air/sea and not for people driving or walking over the border.

In any case, I myself (an american citizen) have been treated with extreme disrespect and a total lack of professionalism when crossing the border at this same checkpoint by car from the Canadian side to the American side. The particularly ridiculous part of this was that after I waited an hour for them to tear everything apart in my car looking for contraband -- at which point it's been verified that I was doing nothing wrong -- they continued to be completely antagonistic.

Edit: I filed a complaint about this, which did lead to a supervisor calling me back and talking to me on the phone for probably 30 minutes. The supervisor was reasonably pleasant, but unapologetic. (Is it reasonable that someone be forced out of their car in the middle of winter and not allowed to get their coat?) He claimed that he put a "warning" on the officer's record, though this didn't seem credible. He again and again seemed to imply that I might have been smuggling, after which I had to remind him that my car was extensively searched and cleared.