[Retric]

The number of tunnels seem excessive, I don't know the drug numbers but let's use people.

A tunnel large enough to walk though could send 10 people a minute without problem. While 24/7 would be near impossible to achieve, it’s 600 people an hour, 14,400 people a day, and up to 5,256,000 people per year.

[kardos]

You need to build tunnels at least at the rate that they get discovered. Also if there's excessive traffic at one tunnel, it's more likely that it'll get found. A distributed network of tunnels is much better for business.

[Retric]

Sure, I am probably also underestimating how many drugs get sent past the border. But, the point still stands you can send a lot of stuff down a tunnel where loading and unloading quickly become the largest issue.