The druswould seem to me less risky. Higher profit margin.
I wonder how long it functioned as a drug tunnel? Years?
The more humans involved on either side, the greater the risk.
That's a good comment, the BP probably can question immigrants they catch.
On the other hand, a tunnel like that, I'm sure one could ask for handsome fees to travel it. A few thousand? Something.... <---- that is, if it is safe enough for humans to use and I assume it is. Maybe humans did use it. Who knows how many tunnels there could be like that. A bit of an engineering feat to make such a tunnel.