Evidence keeps piling up that New York City’s public school system is run for the sake of the adult “stakeholders” — not the kids.

Start with Susan Edelman’s exposé in Sunday’s Post: Turns out city rules let schools hand high school diplomas even to teens who don’t show up for class. That lets the adults boast about results without mentioning all the graduates who never put in much “seat time.”

One ex-student recently told The Post he was stoned or drunk for most of 11th and 12th grades — but still got his diploma six months early. Schools often barely go through the motions of requiring special makeup assignments: One teen, for example, turned in “random nonsense,” his teacher said, and passed nonetheless.

The piece of paper means nothing without the learning it’s supposed to symbolize. But the statistics look good: “Graduation rates are up,” Mayor Bill de Blasio boasted in January. “Yet another record-breaking year.”

Adults also win from the city’s “absent teacher reserve” system — which ensures that teachers no school will take still have jobs. That keeps their union happy — no matter that, as Edelman also reported Sunday, it’s now costing the public $100 million a year.

Keeping unions happy at students’ expense is the rule even for many “moderates,” like Joe Biden. Visiting with the city’s United Federation of Teachers on Sunday, he vowed a “generous” raise if he’s elected president — though setting teacher pay is a state and local matter, and New York teachers do very well for working less than 10 months a year.

Shamelessly, he also cheered teachers strikes like the one underway in Chicago as “courageous” — pretending that they’re somehow about the kids, rather than about union power, pay and benefits.

True courage would be about staring down the unions to start delivering for the children.