6 months after 9/11, I go to the US with a friend, riding shotgun. At the border, the immigration agent did not even look at my face, even though my father looks just like Saddam Hussein. Total stop time? 30 seconds, and that includes looking in the trunk where there was a single 12-pack of beer for the friend we were going to visit.
The most trouble I ever had was when I was on the train, without a return ticket, going for a long week-end to meet a friend and drive up with him. When he saw I had more than enough cash, he told me to have a nice trip.
I once crossed along by car with 2 French citizens, and we had to go inside. Once they saw my medicare card (we didn’t need a passport back then - this was in June 2001), they totally lost interest with me, only being mildly amused when the French guys bursted out laughing at the "Are you a member of a terrorist organization" on the immigration form they had to fill
But the best was when I was regularly travelling with European diplomats with diplomatic passports, those crossings simply took no time at all.