I agree. I am a dual-citizen of Canada and the U.S., and I hate travelling to the U.S. because > 50% of my interactions with the U.S. border folks are suspicious of me because I'm a dual citizen. There is something wrong with a system that is set up to assume that people are lying to you when in reality they may be confused.

IMO, better people training is required—but that requires spending money on soft-skill stuff that the U.S. doesn't want to spend on either CBP or TSA agents.

The absolute single biggest problem with the way CBP works (especially for non-citizens) is that a CBP agent with a bad attitude can decide to reject your entry for no reason whatsoever and no right of appeal. (The second problem, at least at Toronto Pearson, is that some of these folks apparently hate working in Canada. If you hate it, get a fucking transfer. You're a guest in Canada, and it's a great place to live. Stop being a sourpuss because your bad attitude is making it worse for all of the people you interact with, and you're a representative for the U.S. Do you really want to give a negative impression of the U.S. based on your attitude?)