They can do it retrospectively. Logistics knows every single container, it's tax and import consequences. This is a shit take. Seriously, the bill of lading for every good in and out passes through somebody who can total that stuff up.

I am amused as anyone else but this doesn't even count as a glitch to me.

Booze is taxed by %alcohol. You think they ka-ching some cash register at the inter-modal depot? It's done on paperwork, monthly or quarterly.