VAR is always going to be reliant on the judgement of those operating the system - there's no obvious way of overcoming that. I don't agree with every decision that VAR makes but that is obviously true of refereeing in general.
I don't think there's really any evidence to suggest that the 'bigger' teams get a better deal with VAR. I remember Portugal having quite a debatable handball given against them through VAR against Iran at the World Cup last year, a goal given to South Korea by VAR helped knock out Germany, Brazil thought VAR should have disallowed a Switzerland goal against them but it didn't, England thought they should have had a penalty against Tunisia but didn't, many people thought Chelsea should have had a penalty against Norwich in one of the first games in England played with VAR, most people thought the Tottenham goal against Rochdale that was disallowed through VAR was the incorrect decision...