They should never happen. And at that level I don't think they do happen (at least not consciously), as the ref team is being evaluated on each call.
I thought they did a good job with the new Instant Replay. In LA you had two of the most experienced referees in MLS manage to not call that clear and obvious PK. I wish someone would tell us how and why that happened. Was Stott just not going to contradict Maruffo? They both have very (unrealistically) high thresholds when it comes to PKs IMHO. Stott especially over time seems to have gotten much less likely to call a PK. I'm sure someone has those stats and can prove me wrong now that I've said that.
The threshold to give a PK is a lot higher than taking one away with VAR. Just like the threshold is higher to give a PK than to cancel a goal for an offensive foul. Both of these are human nature things and continue to be a big problem with VAR. The system should not be leading to fewer goals overall.
Paul Gardner of Soccer America is really the first that I've seen really bring up the idea that VAR is much more likely to take away goals than award them. This article does a really good job of summing up the two non-PK awards in MLS. https://www.socceramerica.com/publi...-and-var-follow-english-lead-by-going-ea.html
I think it had to do with where they thought the contact occured/began. Don't know any other reasonable explanation. Unless they thought he went down to easy which is why they never called a PK when Bruin went down in the box. But that doesn't seem reasonable to me based on the tackle.
If Will Bruin had his hands on a players back and the person fell down then he headed the ball into the net... I think you are right, they would have waved it off. But I am not upset Bruin didn't get the call, not sure it was worthy of a PK even if that may get called outside the box.