They are more complicated than you state. Crew need to navigate long distances in open ocean, handle rough weather, and perform docking/unloading. These subs have control systems, ballast tanks and pumps. You need both training and experience.
Mismanagement can cause swamping or sinking. The management loses their vessel and their cargo.
Basically, "just random poor farmers that took a pay day from a cartel" is simply not possible.
"perform docking/unloading" LOL. Pull up on a beach in the middle of the night and grab the bricks out of the sub for the guys waiting for you there. This isn't a commercial port with cargo cranes, industrial equipment, and all that. As for handling rough weather, it's a sub. What's going to happen? It's going to sink?
Yes, it will sink. These are semi-submersible "narco-subs". They have weak hulls and little reserve buoyancy. They have very little margin for error in heavy seas.
> Pull up on a beach in the middle of the night and grab the bricks out of the sub for the guys waiting for you there.
Beaching (and getting off a beach) is a bit tricky for semi-submersible narco-subs. You need the right water depth for approach and departure - otherwise you can get grounded or stranded. Waves can swamp you. These subs are cheap - they have simple propulsion and little reserve power and have difficulty making tight corrections.
I am not sure why people are thinking it is as simple as driving your bike. It needs both training and experience.
> Crew need to navigate long distances in open ocean
Not incredibly difficult these days with GPS. Especially if they're doing an Atlantic crossing, its not like there's a lot of things to hit. They're all diesel-electrics, they spend a lot of their time practically at the surface. When they need to dive, its usually only for a few hours at a time, a compass heading is good enough for those times especially in the open ocean. Its not like they're trying to read complicated sonar outputs or anything like that. They're not busting out a sextant to figure out their latitude. They also aren't explorers trying to chart out a new path, they're pretty much going to follow the known good routes other boats have gone before.
> perform docking/unloading
I imagine there are more than just the people operating the boats at the docks. I also don't think it takes a lot of training and skill to pick things up and set things down. And its not like they're having to be some certified harbor pilot bringing in the boat into the shipping lanes, its going to be some little dock off in the middle of nowhere far away from other traffic.
They could learn the ropes of how to operate this thing in a few days along with some good basic documentation, assuming the farmers are literate. Its not like its that hard figuring out "this handle makes us dive, this handle makes us go up, don't go deeper than this, make sure batteries stay within this range, follow the GPS route".
I'm not saying these couldn't possibly be well-trained people operating these vessels, but it doesn't take too much training to figure out how to operate one of these things.
Mismanagement can cause swamping or sinking. The management loses their vessel and their cargo.
Basically, "just random poor farmers that took a pay day from a cartel" is simply not possible.