Running a shop to repair something that weighs north of forty tons implies you're a fairly ethical person. Large tanker trucks for example hold a capacity of 11,000 gallons (14.6kl). This can be anything from milk to salsa, or more typically gasoline or Methylene Chloride. Hacking around in the internals of the computer that controls the engine is generally a dangerous idea as trucks use their engines to slow themselves on hills, or control themselves during ascents much more than their brakes.
I guess 'everyone has a price' in my field is the greased palm you take when someone asks you to compromise your ethics. Sure, you made way more on a routine service overhaul than you normally would have, but gojo doesnt make a hand cleaner to wash off what happens when your work is directly attributable to a major accident or fatality.
