Many of the issues with borderline calls basically boils down to the standard of officiating. Refs are still scared of making the big calls against the top 4-6 teams. VAR was never going to solve the subjectivity of interpretation, and better training/vetting of refs is the answer there.
The people who run footy are so arrogant and I genuinely can't believe that they haven't just borrowed some basic techniques from other sports who have used video tech for longer:
- From rugby; mike up the refs and display the replay on stadium screens. Refs don't need to be sent to the touchline. Have some transparency over the conversation that is taking place and the rationale behind the decisions. The decision should always be made by the on field referee, with the TMO merely providing the images and a second pair of eyes to help him work through that decision.
- From cricket; have a margin for error on offsides. If it looks like over 50% of the player's body is offside, then it is offside. If he is level by 50% or more then go with the 'umpires call', and the original decision by the linesman stands. How one judges 50% or not should be a matter of instant reaction, no measurement required. There will still be some marginal calls in there, but drawing lines and trying to quantify it to the nearest millimetre is king cnut stuff.
It's literally that simple.