I'm wondering how possible it would be to have garbage trucks identify valuable materials in trash as they enter the truck, so the city can fine someone who doesn't separate.
Good luck enforcing these kinds of things. States like Washington have constitutional privacy protections that extend to curb side garbage collection. The state, or an actor working on behalf of the state, can't look through your garbage. I know a number of lawyers here who are waiting with baited breath for the wrong person to get fined based on what's in/not in their garbage in Seattle.
Privacy, other people putting things in your can, previous tenants and perhaps other flaws exist. That's why I think it best it be automated and take more than one offense.