A friend of mine works in a bank. He said, "Did you know, the optimal amount of fraud is actually not zero? Because first of all, you can't get zero, and second, if you try, you screw up the whole bank."
The optimal amount of fraud is close to zero, but it's not zero. (He didn't say if they knew the actual number, but they probably do.)
I think the same logic applies to a lot of other things as well. You want to get as close to 0 as you can, without breaking everything else.
In real life tradeoffs always have to be made, and some of them are tough for the public to know about.
The classic case is road construction. Road design A will cost $120M and 3 people per decade will die. Design B costs $180M and kills 2 people per decade. Which one do you build?
The optimal amount of fraud is close to zero, but it's not zero. (He didn't say if they knew the actual number, but they probably do.)
I think the same logic applies to a lot of other things as well. You want to get as close to 0 as you can, without breaking everything else.