Metal thieves have always had a market for their ill gotten gains - and still have. As with most legislation of this type, all it has done is inconvenience law abiding people.
Often the problem with this type of crime is that the thieves have an inflated idea of the scrap value. The media will report that thousands of GBP of cable has been stolen where in the real world this is the actual cost of replacement where labour and equipment costs far exceed the cost the item.