People sometimes carry tens of thousands of dollars in cash to buy cars in-person. It’s more common than you think.
So they can advise where the cash comes from. The problem wasn’t carrying it it was not been able to give an adequate explanation as to its origin.
That process requires a lengthy and expensive court case and even then sometimes they don’t get the cash back.
Also even if they give an immediate explanation to the officer they are pretty much guaranteed to take the cash anyway. The cop has a financial incentive to do so and will assume the victim is lying.
The possession of the money is treated as probable cause. The police are not tasked with finding the ultimate truth of things, just acting on probable cause.
So you’re on the road with $10,000 in cash. The police find out. You tell them the true reason. They write it down, then seize the money because it was suspicious to you to carry $10,000 in cash.
Then, of course, you can go petition to get the money back. At which time, you have to prove by a preponderance of evidence (the same bar as if you were suing them for damages) to get the money back.
