I really don't understand why we can't just copy the successful implementation of video refereeing in numerous other sports. Or even the (surprisingly!) successful implementation in the last World Cup. Every competition seems to have different rules at play, it's ridiculous really.
In cricket, the umpire's on field call stands unless it is clearly wrong upon viewing the replay. In the case of whether something is hitting the stumps for example, there is a margin for umpire's call if anything less than half the ball would have hit. You get a few whingeing gits but broadly people tend to agree it works very well.
In the last World Cup when they had a screen the referee could go and watch himself, he was allowed to use his discretion based on whether he thought it was serious enough to overturn.
Given the above examples, why anyone thinks it sensible to overturn decisions based on the finest of margins judged by some faceless ref in the gods I just don't understand. VAR can work, but it must be implemented sensibly and consistently in all competitions in the same way. If the system isn't working, fine, tweak it and try again, but there shouldn't be licence for every competition to invent their own systems as they go along.