Disgusting. The whole idea that you have to prove you earned cash legally to keep it is problematic, the authorities should have to prove it was aquired illegally to confiscate it.
If they do have the right to confiscate cash without proof, there should be a fairly high minimum amount, that is the case in many countries. I am surprised they can legally confiscate a few thousand dollars.
We only have protection from unreasonable searches and seizures.
The courts and the police are too closely related. Accordingly, the judiciary is not an effective check on the power of law enforcement, and they often encourage enforcement to make ridiculous seizures for the enrichment of the public treasury.