School lost my 4 y/o cousin on the 2nd day of school

TL;DR

He was found 0.6 miles away from the school by police.

My cousin (child's mom) hasn't received any sort of apology from the teacher nor a phone call the day after it happened saying "your child isn't at school today."

They've met with the superintendent but his approach to the situation lacks compassion and understanding.

What would you do if this happened to you?

HERE IS THE LONG STORY

First day of school (Transition Kindergarten), my cousin, let's call her Mary, takes her son, let's call him Jack, to school. Now before this he was in day care, so this is his first time experiencing school in general. Mary has an older daughter too that is in high school, went to this same school. This school is actually supposed to be one of the top schools in the best district in our city.

So anyway, first day of school, Mary notices that all of the other kids have laminated name tags on, every one except Jack. So she asks why he doesn't have one, teacher says "Oh what's his name?" "Jack ____" "Hmm, it must be because he was a late registration." "No, he wasn't. But I understand if there's miscommunication in the office. Its okay."

Totally thinking that he'd probably have a temp sticker tag in the mean time...

Well he didn't. Even at the end of the first school day. And again on the second day he still didnt have one.

Well now it's the second day of school. Dad comes to pick Jack up, walks up to the teacher and says, "Hi I'm here to pick up my son Jack ____." Teacher says, "Hmmm... Jack... hmmm" She turns around looking into the classroom and he is no where to be found. So then of course everyone starts looking for him. The principal, teachers, parents, police. Eventually the police find him 0.6 miles away from the school. He had followed another child out of the classroom because he liked his "minions" backpack, you know from Despicable Me? And the teacher DIDNT NOTICE that he was missing. On the first day of school (and the superintendent reassured this) they say that the protocol is to have all children sitting on the carpet in the classroom and when the parent comes to the door the teacher will call the kid to leave. If that's the case, how did a child leave the classroom AND THEN leave the secure black iron gate all without the teacher acknowledging his parent or just not seeing him. A bit ridiculous on the second day of school in my opinion.

Personally, I'm a step mother to one and a nanny for two so from both aspects I see wrongdoing. The parents should teach their child not to leave the classroom or the school property. Sure. That can be an argument. But isn't it the teacher's and school's job to ensure their safety for a couple hours out of the day????

What do you think of this? What would you do if you were the mom? The teacher? The superintendent?