Just a few days ago, I made the mistake of telling the police how much cash I had with me after they stopped the taxi I was sitting in (a few hundred euros). This happened in the middle of the night in a foreign country (France), so I didn't dare to disobey their orders. They took the cash and drove away. It turned out they were not real officers, but only dressed up as such for the purpose of robbing gullible tourists...
The same situation in many developing countries around the world. The local taxi cartels have been using lobbying and outright violence to keep ride-sharing services away / banned.
According to the article, the officer directly asked him if he had a large amount of US currency in the car. There's no way to weasel out of answering that kind of direct question if you've already been cooperative with other questions. It's possible, though uncertain, that he might have kept his money by categorically refusing to talk from the start of the stop.
With state cops you are allowed to lie under many circumstances (exceptions: identification, under oath, on reports and forms).
He could have just straight up lied, or interpreted the question in a way favorable to him (I thought you meant millions, not less than $100k).
He cooperated at all points and was doing nothing wrong. The logical conclusion is that being truthful and cooperative is not going to keep you out of trouble.
In the US, that doesn't mean anything legally speaking. They might know then that this means you have a lot of cash on you, but that's not probably cause for a search. They still have to get permission or a warrant to search.
I don’t know about probable cause for a search, but legally speaking, clamming up to a specific question, as opposed to explicitly invoking the 5th amendment right, currently means something in trial, as ruled in Salinas v. Texas.
Second, in the US at least the government does recognize a limited right to privacy in the form of the 4th amendment which spies to States as well. An officer cannot search you, your car or your home without a warrant from a judge or a tangible reason to believe you are committing a crime.
That's why the statement at the top of this thread is
> The lesson here is clear: do not cooperate with the police
Suddenly clamming up is a problem, doing so less suddenly is not (I'm elsewhere in this thread roughly advocating for clamming up about anything not directly related to the traffic stop)
The correct way to handle this during a routine stop is to inform the officer that you do not answer questions. In the US, you are not required to answer any questions.
Also, the police have a limited time to conduct the stop. Once they give you back your license, you can immediately leave regardless of what the officer requests that you do. The stop is over at that point, and they cannot legally detain you any longer.
> officer directly asked him if he had a large amount of US currency
That reminds me of something I think I read. Is there are companies that specialize in identifying motorists that are carrying large amounts of cash. They make money by selling that info to the police.
We know for sure that this cooperation led to the money being seized. We can't know if staying silent would have led to a different outcome.