emrdoc - I agree totally. My feeling at the time, when the officer admitted lying, was disappointment as a member of the community. It didn't matter in my little case, but the same actions in a case such as rape or murder could result in a violent criminal walking free. To me his behavior was a slap in the face to the very notions of 'law and order' and 'tough on crime.' That said, I would never bring that aspect up to a border agent. I was looking at 'mitigating factors', as I have read that consideration for TRP involves an in depth look at each particular case. The totality of circumstances clearly show this was a one-off, bad luck encounter that escalated due to confusion and mistaken identity - the officer thought I was a burglar.
HomoEconomicus - yes, I was hopeful about that at first, but it is not much help in practice. Many states now have mandatory jail as part of a DUI conviction. It has been reported that the new policy of waving TRP fee was a token gesture to the tourism industry that has not eased entry in any way.
A quick stab at the math: Recent Canadian Trade figures indicate about 20 million visitors a year from US (figure is five times higher if using daily border crossers). 20 million is about 6 percent of the US population. There are 1.4 million DUI arrests in US each year. All things being equal, that would mean about 90K people with recent DUI flags enter Canada from U.S. each year. Figures for those turned away are harder to come by - 2006 figure was less than 7000. That would mean a less than 10% chance of being stopped. I realize these are all wild estimates, but it is a place to start. It seems that there are many more recent stories about this being an issue, so I would guess that the figure from 2006 is no longer even close. I suspect the number exploded after 2009 and is probably 10 times higher. That would explain the recent actions by the tourism lobby - this was simply a much smaller issue five or ten years ago.
I thank everyone for the constructive discussion - other similar threads have quickly gone off the rails. I would love to hear from a current/former Canadian Official on the current state of affairs, but I suspect this is a touchy subject.