For the critics who say it's "unbelievable" and "unrealistic"

It's not. We’re talking about mid-teenage girls here, who are subject to all kinds of questionable whims rooted in immature emotions. Look no further than Taylor Smith, who pushed Jordan Holgerson off a 60' high bridge at Moulton Falls near Vancouver, Washington, on August 7, 2018. Here's the actual video: https://www.youtube.com/shorts/3CcJ6GxcbBk

As for the potential transgression in question, look up what happened to 16 year-old Skylar Neese on the night of July 5, 2012, in the Morgantown, West Virginia, area, which is featured on the real-life crime series See No Evil, Season 1, Episode 6. You can read about it in brief here: https://en.wikipedia.org/wiki/Murder_of_Skylar_Neese

SPOILERS

We learn in the surprising climax that there was no crime involving Kayla maliciously pushing Britney off the bridge. It was all a ruse to allow Britney to visit her boyfriend in place of going to ballet camp with Kayla hoping the pseudo-tragedy would bring her divorced parents back together. That last part reveals why Britney didn’t just have her beau pick her up at the bus stop.

The bridge in the woods was a known hiking trail and Britney just had her guy pick her up at a parking spot a little further down the trail. Being preplanned, Britney faked having to pee just before the area where the bridge was located, which forced Kayla’s dad to stop. Britney thought the elaborate hoax would be funny, as explained by Kayla.

Is this unrealistic? I don't think so. It reflects the creative whims & deceptions for which school girls are sometimes known. It’s exceptional, yes, but not exactly unbelievable. The fact that the girls didn't think through the potential dire ramifications of their ruse shows their immaturity.

As for the issue of Kayla’s parents unrealistically disregarding surveillance cameras in the well-to-do neighborhood of Britney’s father, they weren’t going there to commit a crime, but rather to plant Britney’s phone in the ground near the father’s house (theoretically, no one would find the phone since it would be hidden in the ground during winter; and if the detectives ‘pinged’ it they’d simply discover it’s in the area of Britney’s house). Since no crime would be committed in doing this no one’s likely going to be motivated to scan through hours of dull surveillance footage.

Lastly, running the father over wasn’t planned. They were driving down the residential street (in an area where there was no surveillance cameras) when the father rashly jumps out into the street to stop the vehicle. In a split second of passion & insanity the mother decides to step on the gas and mow him down. It wasn’t a premeditated thing.