Can U.S. Customs seize a truck driver’s lunch if there are any beef products in the lunch bag? And, why is the Canadian border almost never backed up like the U.S. border?
Rule Number 1 about U.S. Customs: they can do any bloody thing they want. Actually, while it may seem like an extreme measure, they’re very serious about keeping any possibly infected beef out of their country, and if that means looking into your lunch box, they'll do that too. I think I'm safe in saying that if the situation were reversed, Canada would be taking similar measures. The risk of infection is low, but the potential losses are enormous. Remember what happened in England a few years ago? Nobody wants that to happen here.
And as for the second part of your question: we have a more efficient clearing process, and we're not looking for terrorists, infected beef, explosives, illegal aliens, and truckers with criminal records. That's what creates the delays. If we ever get serious about border security, I suspect it'll be the same crossing into Canada as well.