Unfortunately the issue with refereeing is cultural, and it's not going to improve.
The sport and fans treats referees with contempt, with conspiracy theories abounding and abuse completely normalised. "The referee's a wanker" is possibly the best known chant in football. People laugh and congratulate managers or players who openly abuse referees or accuse them of corruption.
That contempt reaches the grassroots where there are fewer young referees than ever before because they keep getting abused and assaulted and quitting. Anyone teenager with anything better to do goes and does it after being spat at or punched by some 35 year old hungover twat.
Fewer grassroots referees mean you a shallower talent pool, which means fewer professional referees of the correct standard.
That's where all of the Premier League's problems begin. Mike Riley does everything from the perspective of protecting the referees that work for him, because they are an endangered speices. 2 top PL referees have recently quit because the abuse wasn't worth it. We have parachuted in an Australian to boost numbers.
Why don't retroactive fecisions happen? Because they don't want to publicly undermine referees by overruling them. Why do we have "clear and obvious error" bullshit? To protect the referees. Why don't we hear VAR/Referee conversations? To protect the referees. Why don't referees get demoted? Because there's no good options to promote.
There are some issues around the laws being written in a oblique way, but mostly the issue is that no one in their right mind would ever want to be a referee.
The sport and fans need to change the culture around referees and then we might attract better ones. I'd start by giving us the feed on their mic as per Rugby, and heavily fining every player who is abusive towards them.