The raw number of dollars per pupil isn't the only variable here, if it were the US would already have the best schools pretty much everywhere (the US spends WAY more than the average in this category).

There's also what percentage is spent on administrators instead of teachers (frees up money for teacher salaries), various QoL improvements that could be made such as less paperwork, more latitude in how they teach, hiring a few full-time graders to take some of the load off teachers (generally a big time-sink and a source of a lot of overtime for teachers).

> When the school gets more applicants than places, how does it decide who to let in?

Presumably either entrance exam or lottery depending on the philosophy of the school.

> Seems preferable to intervene and improve failing schools before it gets to the point of shutting them down.

Do we know how to do this in practice? I haven't heard of any tactics that reliably improve a school that has started going downhill, but if you have some examples, I'd definitely be willing to consider them.