I worked as a security consultant for a multi-national company working in Colombia. The Guerilla groups ELN and FARC routinely took protection money from contractors who supplied this company ,in the foot hils of the Andes. It perpetuates the whole Guerilla/terrorist thing, as to be perceived as a threat to these transport companies, they have to keep up a level of operations to make them a credible threat. The money received from these companies allows the guerillas, in turn, to maintain their level of operations. Whats the answer? Military protected convoys, with the resulting percentage loss of materials and personell, OR pull out!
What we're essentially talking about is that our logistics chain runs through enemy lines. It's as if our men in Hohne during the Cold War were supplied through Gdansk. Hilarious, I suppose. But what is one to do? Reach an agreement with Iran? China? Devote thousands of extra troops to convoy protection - including on sovereign Pakistani territory?
PIRA (and the Proddy gangs) became dab hands at scamming the EU (piggy smuggling, fuel smuggling etc), and squeezing protection money out of taxpayer funded building projects in the 80's. Do a Google for "Financing the Provisional IRA". Albanian bandits were robbing UN soldiers of their vehicles in the run up to the Kosovo job.
It should hardly surprise us that folk with banditry in their DNA should act this way.