Why the Hassle at the border?

[Beenaroundabit]

But they can hassel you for whatever reason they can come up with (even when you have a GC). And they don't even need to have a reason: I got held up in Minneapolis/St Paul in April for no reason what so ever (I asked when it was finally my turn, and the TSA agent told me that everything was in perfect order. Yet I was detained at Secondary questioning for over an hour ...)

Just because the person being inspected doesn't know the reason why they're delayed, it doesn't mean they were delayed for "no reason at all." And actually, a person entering the U.S. has no way of knowing why they're stopped - unless they're privy to what came up on the computer when they were initially inspected. As someone who has been in the shoes of that inspecting officer, there's no way on earth they're ever going to tell you truthfully why you were stopped. Suffice it to say that sometimes it's an issue that delays you for a certain period because it requires additional research by a secondary officer. Sometimes it's the computer system, itself. Sometimes it's a certain traveler profile that you might fit.

I can also tell you for a fact that they do not stop people for the fun of it and "hassle" them for no reason at all. There are more and better things for them to be doing.