Not really, they know there's a high chance they're going to get picked up.
I spent a summer working the counter-drug maritime operations mission; there's a lot that goes on that most will never be aware of. Never mind the legal aspects, just the interdiction's alone are fairly well coordinated.
These home grown, jungle built subs (BTW, they don't actually submerge, they're more of a Hunley type sub, where the snorkel/sail is always above water) are nothing new. It is (however) pretty ingenious, and seeing how they're made is pretty enlightening. "Necessity is the mother of all invention" so-to-speak.
The thing to keep in mind is that these "submarines" are disposable, and have the life expectancy of one drug run. These subs are literally built around the engine and drug pile in the jungles, and slid into the water when complete.
