When you consider your last point about them flying to other countries to referee matches and the fact that they are being paid by those associations for their work coupled with the fact that they have zero accountability other than "sorry" it's not really a far stretch to assume that some if not many matches are subject to being paid off for outcomes. Our match certainly gets most of the highlights considering the fact that there is a country who has a history of infractions in football and will do anything to generate revenue by any means possible. Am I saying it is an absolute fact? No, and my post may come off that way and if it does it's not my intention but to think that there isn't a financial operating factor in referee decision making now that you really have zero visibility into what the man in the box is doing or how those decisions are being made you certainly can't rule out that they have bias - external influenced or just plain incompetence, I lean towards influence because no one can be that stupid/incompetent. Wherever there is large scores of money you can 100% assume there is a level of cheating going on that isn't blatantly obvious and will never present itself unless you see a pattern whether its teams cheating, or the managing system being corrupted.
To fix this the league and the FA have to really just find a way to introduce penalties post review to ANY game that is deemed to have the ambiguity associated with decisions. But we both know that is never going to happen because the last thing they'll do is call one of their own incompetent and it opens a can of worms no one wants to deal with so you get refs getting away with whatever decision they make because no one can challenge them. If I was a corrupt business wanting to gain leverage that looks rather ripe an opportunity.
P.S. Apologies for the late reply but the last two days have been busy.