In what world was Khan not robbed by Peterson? 2 point deductions from the ref, and he was on PEDs.
Obviously, not every single fight will be a robbery. GGG has a 'name' in the US, while Jacobs was a novice in comparison. The robberies im alluding to generally involve a fighter who's a "visitor" that the local judge either isn't aware of their reputation, or is someone who's expected to take the belt back to Europe or Asia.
It essentially comes down to either human psyche (being influenced by the crowd or ignorance); or economics. A US or Mexican fighter who fights in the States generate revenue for the local tourism, stadium, taxes, and businesses that benefit from fan spending. Whereas someone taking a belt away to another continent is a loss of an entire revenue source. Remember, these judges work for the State.
Had the Jacobs fight been GGG's first or second on US soil, then he may have lost the decision easily.
*These are all observations and hypotheses.