How do you handle situations with lost luggage? First, the person walks through with just a carry-on, but I suppose that's not suspicious if they show you their lost bag tracking number.

Then, when the bags do arrive, does Customs search all bags that arrive after their owner, or it is also just random?

Seems like a smuggler may choose (or not choose) a flight routing with a really tight connection in the hopes their bags don't make the connection, so they don't go through customs with their bags by their side.