The topic was not about catching terrorists at all. But even if it were you'd be wrong. I'm sure all the terrorists also used cars and probably brushed their teeth. So what? The point of security is to figure out relevant things - that distinguish terrorist from non-terrorist - from irrelevant. Coming from US/Canada border is clearly an irrelevant thing - millions of people come through and even if one of them is a terrorist treating all of them as a terrorists would be highly ineffective. Moreover, it's even worse than ineffective - it's hurtful. Since the officers can't spend hours on every border-crosser, each innocent they wrongly detain raises the chance that they won't have the resources to inspect the real bad guy, because they were busy with harassing the good guy. The fail here is that they denied entrance to the innocent. Imagine spam filter that would put a lot of legitimate email into "spam" folder - would you argue it's an excellent thing to have because once 10 years ago you had one spam in your inbox - or would you argue it needs to be rewritten and fixed so that the false positive rate would go down? Nobody argues for no border protection at all. But border protection that confuses protecting with harassing the innocent has clearly lost the vision of its purpose and needs to be reminded of it. And if somebody from the personnel can't understand the difference he should be given a job that doesn't involve contact with people - like cesspool cleaning or monitoring early-warning radar stations in the Arctic.