Maybe he owns the truck? When I worked in the oil field in the late 70s early 80s, I heard about independent guys doing this kind of stuff all the time with fluids hauled off the lease. Usually it was just salt water with other oil and crap mixed in. It wasn't unusual to go down a back road and see a trail miles lone where he cracked a valve and drove off. It saved him paying for disposal.
It got so bad at one point, under cover cops, working with my company would follow the waste haulers all the way to the disposal site where they pumped it back into dry holes. One scumbag was backing into what looked like a turn around but behind it had a fairly steep hill that ran down into a reservoir. They caught him, but an entire hillside was wiped out for years. It was apparent that he'd been dumping there for some time.
Thanks. I wasn’t looking at it from the economic standpoint. I immediately went to someone being lazy. Saving cash makes way more sense.