Everyone inside Venezuela needs US Dollars, whether for international trade, to work the currency exchange operations, to hedge against the next imminent devaluation of the Bolivar, or for their upcoming move to Miami. Such a demand spawns bulk cash smuggling into, not out of, Venezuela.
Whilst we are not US Customs and Border Protection (CBP) agents, as bankers:
(1) We know when an existing client's request for dollars is inconsistent with his trade of business.
(2) We know when a client's cash receipts, that ordinarily are deposited the same day each week, are no longer being presented, and when cheques from a new payor have taken their place.
(3) We know when clients whose business takes them to Caracas once of twice a month on average, are now visiting Venezuela twice a week.
(4) We can tell when a client has unexpected and repeated cash withdrawals, when all his previous traffic was in cheques and wire transfers.