I saw this as a reporter. If kids dropped out after a certain deadline, the school districts still collected their state funding but didn’t have to spend it on kids who weren’t there. They considered it a smart way to fund the smartest students.
See?
Some public schools may do this with high school students but I suspect charters may do this on every grade level — one of the little secrets of charters is that they have a lot of turnover.
They’ll accept a kid, then find out the kid has issues that make their behaviors challenging, or that the kid threatens not to score well-enough on the standardized tests. The kid gets “counseled out” of the charter and is sent back to the public school. (Two of the best known charters, KIPP and that school in Harlem, are famous for this. It’s one of the ways they keep their achievetment stats looking good.)
I suppose that depending on how the state calculates charter funding, the charter could end up with a nice profit — and the public school then has to teach and provide supports for the kid without any funding.