According to this web site, one of the highways I travelled on carries 10,000 cars per day. Let's say the average stop takes five minutes, the average car has 1.3 people in it, and the value of people's time averages $15 per hour. This means that each arrest costs a little under $60,000; perhaps there is a deterrent effect as well. Is this worth it? I really don't know.
But I can't help but notice that over the last ten years, the US, as a matter of security policy, has really gummed up the ability of people to get easily from one place to another. Is it a coincidence that the economy has underperformed over this time? Perhaps. I can't think of a way to run a regression to test the relationship between ease of travel and economic performance--but that doesn't mean that someone else can't.