Yes selling fuel is rampant in some parts of the world, notably West Africa and some parts of S.E.Asia. I'm very familiar with this and have been involved in finding ways to stop it.
I was engaged by one Oilco. to investigate fuel stealing on an operation in Papua, Indonesia, where I found one little tug that was tied up alongside a grounded barge as standby vessel and standing dry half the time, but reporting fuel consumption eqv. to steaming at full speed 24/7.
Another Oilco, this time operating in the Mahakam Delta, East Kalimantan, Indonesia,found that abt. 25% of the fuel supplied to the boats and swamp rigs hired by them "evaporated".
I was engaged to train their Marine Inspectors in how to detect and stop the theft by explaining the different methods used, especially on the fuel supply LCTs.
It was a waste of time, since most of them had been engaged in the racket for years and probably knew more ways then me.
Colouring the diesel green only resulted in every truck and boat in the area running on green fuel.
Nobody find anything wrong with Tidewater abandoning their crews to their faith in a country not known for it's fair system of Law enforcement?? I know they were not Americans, but still???