Yeah that’s fair, you might need to make the formula more complicated. The goal though would be to alter what we have now, which is extreme differences in quality between schools in rich areas and schools in poor ones, to a model where everyone can access a similarly decent quality of public schooling. Maybe the formula would need to look something like

(the money required to maintain the school building) + (a wage thats similar to the wages for other teachers in the state, with cost of living factored in) * (the best teacher to student ratio achievable across the state) * (student count at the school)

You might be surprised to learn that this is how education funding already works. Government isn't completely idiotic.

What you are ignoring is that educational spending imbalance comes from private voluntary educational spending (enrichment programs, camps, PTA), not public mandatory spending.