Laws on cars vary. It is common that cars can be sold for cash without any contract transfer. Same with guns but less so.

However are you saying that someone selling some extra scrap copper is in any way similar to someone selling their gun? These things are somehow equivalent?

However I will show you the actual connection. What you are doing is making the law abiding citizen be punish for the crimes of the criminal. This happens with fire-arms legislation as well.

The result tends to of course be that citizens lose rights while criminals do as they have before.

This is not a world I want to live in and I hope you would not want this either.