Without making a falsifiable claim about who this “aristocracy” is whose assets are the only assets protected by the police, it’s hard to test your statement or see how it provides value.
Do you live in the US? It’s pretty trivial to figure out who is and isn’t allowed to drive around with large sums of money, or carry a loaded weapon, as an actual practical matter.
A good way of thinking about this is to understand that there’s an in-group that the law protects but does not bind. And an out-group that the law binds but does not protect.
It’s a dark vision of the world but there are many in the in-group who seek to preserve it.
"No true Scotsman is not Scottish" seems true, definitionally. Same applies for aristocracy: they are the ones who are served by special interests, by definition.
No policing system is perfect, in any complicated enough system there will always be rules that undermine that system slightly. It's like asking "why is cancer a thing, it undermines living organisms".
If that is the case, why is civil asset forfeiture a thing? It seems to undermine property rights and is a glaring failure in the system.