> Red light cameras, for example, strike me as unalloyed good.

I get where you're coming from, but there's a big problem: our laws did not evolve to be enforced effectively. They are appropriate when they are enforced selectively, with discretion. Many are wholly inappropriate if simply enforced 100% of the time to the letter of the law.

That's not to say we couldn't change laws to work if enforced near-100% of the time, but it would take our legal institutions quite a lot of time to adapt.