Random sampling over time is substantially as effective as having someone enforce the law 100% of the time. It's something like how randomized algorithms can be faster than their purely-deterministic counterparts, or how sampling a population is quite effective at finding population statistics.
It's only unfair if the innocent are punished. Lot of murders go unsolved. Does that mean the murderers that do get caught are treated unfairly?
That's a pretty extreme example, maybe the idea doesn't hold as much there. But yeah, if 99% of murders weren't prosecuted, the 1% who get charged might feel like they were singled out (and maybe they were, because of some bias or discrimination). Again, 100% enforcement is better.
It doesn't just "feel" less fair, it often is -- bc it's not truly random, it's selective enforcement which leads to things like "driving while black".
Definitely true in practice, but I don't think we want discretion. What I mean though is as a deterrent, you can either have a "fair" fine that's enforced 100% of the time, or 2x the "fair" amount with 50% enforcement, etc. When it's 100x the "fair" amount with 1% enforcement, and you see everyone else not being enforced, it feels unfair.
Traffic rules do require some discretion though - if eg you don’t allow crossing a double yellow line but a car is broken down blocking the lane, does that mean that the road is now effectively unusable until that car is towed? Lots of examples.
But I’m with you on more enforcement. I’m totally fine with automated traffic cameras and it was working great when I was in China - suddenly seemingly overnight everyone stopped speeding on the highways when I was in Shanghai, as your chances of getting a ticket were super high.
It feels less fair though. When everyone is driving x mph over the limit but only you get pulled over, it sucks. So I agree for efficiency of enforcement, but I'd rather see 100% enforcement (automated if possible), with more warnings and lower penalties.