Your analogy doesn't hold up, unfortunately. Fishermen may go to the fish but if cops wanted to catch drunks they would sit outside every tavern and bar in town - which they don't. Instead, they stage their dog-and-pony show with no strobe light left unlit on main thoroughfares.
Your categorical statement that society wants a cop on every corner is unprovable therefore invalid. For the record, I certainly don't want a cop on every corner. The fewer the better and I had better see every violent and property crime solved before they get on with the important business of randomly violating the 4th Amendment. In addition these checkpoints are frequently in suburban areas where the car is a necessity and where, by sheer coincidence I'm sure, the local residents have the ability to pay the fines.
Finally, if it's about DUI then not a single ticket should be written for burnt-out taillights, seat belt use, or other revenue-raising 'violation.'
I see that you quote the constitution frequently; you might also want to read some of the other things the writers of that great document said regarding moral behavior.
“Our Constitution was made only for a moral and religious people. It is wholly inadequate to the government of any other.” John Adams
http://www.eadshome.com/QuotesoftheFounders.htm
I hardly find it “moral” for youth to contact their friends regarding where a police checkpoint is setup to catch drunk drivers.
(Wayne Ziese, a spokesman for the California Office of Traffic Safety, said he’s heard a lot of stories about young people using technology to avoid drunken driving arrests.)
Being that the Founders were religious people, let’s see what the Holy Bible has to say about the police:
In Romans 13:4, Paul says a policeman “is God’s servant to do you good. But if you do wrong, be afraid, for he does not bear the sword for nothing. He is God’s servant, an agent of wrath to bring punishment on the wrongdoer.”
You’re concerns are misguided. You need to help put our country back on the course of being a “moral and religious people”, so we won’t have the need for a “cop on every corner”.