Believe it or not, there is a scrap dealer lobby and of course they fight any attempts to do anything that might "adversely impact legitimate business"

Cracking down on the individuals who buy these and making it financially not worth their while seems as if it might be a deterrent. Obviously it’s easier said than done or it’d be happening.

The state created new legal framework to prevent stolen cats from being purchased as scrap, but the thieves just go to another state

Ask the Electric Companies, and The Municipalities. Nationwide, Copper gets a good price, and the Electric Companies have a terrible time with theft of copper wire. People have been known to sneak into Electric Substations, at night, and steal Copper (and perhaps, aluminum) wiring, because of the price it can get, at the scrap yards. It was so bad in Ohio, that The State passed a law, requiring that anyone selling Copper wiring, to the Scrap Yards, was required to "sign off" when they receive payment for it. There was a case, in my hometown of Columbus, where a thief cut down a utility pole, in the wee hours of the morning, to steal Copper Wire from the lines, and perhaps the transformer; knocking out power in the immediate area.

People have gone into vacant homes, and rented Apartments, and "gutted" them, of anything that can be passed as scrap. I've seen storm sewer gratings, and manhole covers stolen, as well as street light wiring boxes, vandalized. The thieves take the Aluminum Covers, exposing the wiring, and maybe take the wiring, itself. This exposes the wiring to The weather, and Children. Iron and Steel doesn't bring a high price, per pound, but a 100-pound Sewer Cover, can net you, $5.