It's not though. It's a fundamental problem with the system.
@Pexbo summed up the omnishambles perfectly. In the context of the Trent handball last night everyone did their job. The referee let play develop when he couldn't be certain about the handball because he knew VAR could intervene if he missed something important. VAR didn't intervene because the footage didn't meet whatever criteria they use for a "clear and obvious error". So yet again., we're arguing the toss about something completely intangible, which is how to set the bar for what represents an obvious errror. And there is no way that can be completely objective. But we have to have some sort of bar, otherwise the game will be constantly fecking stopping and starting with every single big call by the referee getting second guessed by VAR.
The whole thing is an unfixable mess and blaming it all on human fallibility is missing the point. It's also funny as feck because we were sold VAR (and it's infuriating game slowing down, celebration ruining downsides) as a means to remove human fallibility from match officiation. Go figure.