The same is true when flying on commercial flights. Passengers have been flagged detention, search arrest, and seizure of cash for purchasing their tickets in cash and/or purchasing one-way tickets. One of the news stories was about another man who delivered a collectible automobile to a private customer, and he was arrested and his cash from the sale of the auto seized when he tried to purchase an airline ticket for a flight home. The airline's ticket agent was required to call the police when he went to purchase his airline ticket.
The trading of precious metals and coins can also be a target for seizures by LEO.
What you posted proves that we are just serfs again, after the War of Independence, the War of 1812, the War between the States, and all the rest right up to the present. We are back, in fact politically worse off than the typical English peasant of the 16th Century, who at least had clearly defined rights under common law. Today nothing — NOTHING — is immutable. My Rights and your Rights can vanish in a trice, at the whim of a Circuit Court judge.
The 2nd and 4th amendments are being gutted. At least we have the power of the internet, and some damn good Constitutional lawyers working to preserve and reclaim those Rights. Those ‘Inalienable, God-given Rights’.