I suspect the percentage that gets caught on any given trip is quite low. They're playing a lottery with a 99%+ win chance. When they win, they sell the stuff at a huge markup, and when they lose, all they lose is one shipment and one potential courier who wasn't even in on the plot.

Exactly. The "War on Drugs" is never going to succeed when all the smugglers have to do is factor in a loss % into their price; it's simple math.

They still have drug trafficking in Singapore, where you get the death penalty for drug trafficking. I think the key is not to make drugs expensive, but to make them cheap. Then the criminals are out of business.

Yup -- then the key players just make sure to insulate themselves with plenty of lower-tier traffickers.

Drugs will only be cheap when they are legal.

Well, they don't really care if people get caught with it, so long as some make it through.