[NoLinkToMe]

Even if ship displacement wasn't an observable thing, there's no real reason that empty oil ships enter the strait, and then again leave empty, after having obviously docked at an oil terminal, on any regular basis.

Public and observable information makes it trivial to make high-accuracy assessments about the veracity of the claim.

And $2m is sufficient budget to finance spot checks, especially given you'd have to apply them to an exceedingly small percentage of ships. A year salary of an average Iranian police guard is about 5k, for context.

Plus you can create a scenario where fraud being detected is prohibitively expensive, and may even result in the captain being imprisoned in Iran. I wouldn't expect a lot of lies.