Contrary to what many people seem to think, the FA Cup does not start in January. It started back on Friday 6th August at a handful of lowly non-league grounds. Even moving forward 3 months to the start of the Competition proper, this started at Sudbury's modest, but well equipped for their level, ground with their 3G pitch. It is unrealistic to expect all rounds to be treated the same (unless that means no VAR whatsoever).
As for treating all matches in the same round, the same ....... why? Fairness is both teams being treated the same in each game. It seems perverse to not use something which is designed to improve fairness, as much as possible.
(The fact that some of the decisions made by VAR are staggeringly inept anyway is a completely different issue.)
Exactly. ‘Fairness’ comes in many types. VAR existing in one cup game and not another - is not hugely different to a FIFA Elite referee officiating one game, and a L2 official at another. There’s no sporting integrity issue here. Each team has precisely 50% chance of any incorrect decision being to their detriment or advantage in a VAR game, just as much as it does in any other.