I liked this country better when you were free to carry cash and a gun.
If you are carrying cash to buy a car from a private seller and you get stopped, it can be seized. It’s hell to get it back, assuming you can. Last car I bought I arranged to have it counted into the seller’s hand at a bank. But given travel distance and days available that isn’t always possible.
You are aware that drug pushers keep all their money in cash. Why would any ligitimant person travel with thousands of dollars in a suit case???