It's already illegal to buy stolen goods, if someone rocks up at your doorstep with pieces of rail tracks and you buy them you would have a very hard time convincing the court you were not aware they were stolen.
Our problem in not getting a handle on this crime is that it is just impossible to police, back in the good old days if you see someone at a Telkom or Eskom box who is not in uniform, is not driving an Eskom/Telkom vehicle you knew exactly what you were dealing with. Nowadays the dodgy guy who own a scrapyard could be a legit Eskom recycler and you could look like a proper Karen for calling cops on him.
It was easy for the public to assist and the companies were responsive, nowadays no one cares, I once try to alert a Telkom guy of an open box somewhere in the neighborhood, guy told me straight that he would not bother, even advised me not to care too much, it's a big money making racket and it's preferred like that.
The responsibility should be thrown back to the companies because they are the ones creating an enabling environment, law enforcement is also to blame but the public assistance that makes law enforcement effective cannot work in this chaos.