The answer is, you still do socialism, and you also pay someone to go around busting scrap yards that buy obviously-stolen material.
Just focusing on the demand-side dramatically reduced incidences of catalytic converter theft in the US. You still get the occasional attempt, but basically no scrap yard will take catalytic converters without a title to the vehicle with matching VIN, and most will want to see the vehicle.
Yes, requiring paperwork to scrap wiring is bureaucracy manifest. But legitimate people just do not roll up to scrap yards with a van full of tangled 4/0.
The big catalytic converter buyer was so brazen, he had a mobile app. Free markets for stolen scrap is just beyond tolerable at this point.
Italy is no Denmark but you still require to register before selling you scrap copper.
I think it's a reasonable response for a real problem and refusing to do this due to some idealistic free market principle appears to me to be a sign of fanaticism.
Scandinavian scrap metal thieves organize trucks and cranes to steal copper roofs from old churches and rip down railroad overhead lines all the time.
Free healthcare and education, guaranteed housing and social safety nets make little difference.
Some people will stop at nothing to get more, no matter how much they already have. (Applies to billionaires and paupers alike). I guess you could call it having an entrepreneurial spirit.
No one steals car stereos anymore though, because you can't sell them to anyone. That mechanism could be put to more work. Heavy, EU-wide supervision and enforcement against scrap metal dealers would probably make a difference.