To me the problem is that you wouldn't be able to buy a car anonymously anymore, while it leaves the really rich pretty much untouched.

Art is a well known angle for money laundering or giving someone a huge sum of money pretty much without any regulation. Contracts for construction or even consulting are another way.

I don't have access to this kind of playground - chances are, you neither. But the people supposedly targeted by this kind of law (corrupt politicians, organised crime, ...), do have access to these things and are therefore not impacted.