Copper is relatively cheap when you compare it to gold, silver, palladium and platinum, etc. Is the payoff really worth their trouble?
Copper is cheaper than gold but it is more plentiful, easily accessible, and easy to sell at the salvage yard for an immediate return. The initial investment in copper is usually zero and your return from the salvage yard is immediate and paid in cash. A lot of tradesman have access to copper from job sites as copper is used a lot in heating systems and other plumbing. Thieves that steal copper break into abandon homes and rip out the plumbing and heating for the same reason as mentioned above. It's quick cash. I think copper is paying out at 3.75/lb.
It is very easy to steal...and can be found in easily accessible cables and boxes. It's not as cheap as you might think, either. A few pounds can bring decent money to a criminal, and yet they only risk a few months in jail Whereas your chances of robbing a gold or silver dealer are virtual suicide. They are heavily armed, well connected and more than a few robbers who have targeted bullion dealers have ended up in a ditch with bullets in the back of the head. The police do not particularly care about such killings either. Even if you succeeded in robbing a bullion dealer, they are a close knit group and you would eventually be found and killed. I have never heard of anyone who didn't.
True, as you say, copper is relatively cheap compared to other precious metals. However, copper is used extensively in plumbing and electrical wiring; in air conditioners; for gutters; house trim; etc. Copper is so ubiquitous, that it is readily available to steal. The tragedy is that stealing these things from a building does thousands of dollars in damage, and the scrappers who stole it get enough money for a 6-pack and a package of cigarettes! It is a lowly lifestyle! I have no problem with legitimate metal men who get their stuff legally. In fact, I have done a bit of scrapping myself. However, scrappers who are thieves should be shot on-sight!
Copper is used for old pipes in plumbing and in wiring so it is readily available and easier to steal. You can go into an old abandoned building and steal the copper pipes. No one ever made old pipes from gold, silver or platinum and other precious metals. Things made from those types of metals are in high security places. Places under guards with surveillance cameras.