The report you cite from the tax policy center indicates that 30% of variation in school funding is still within-state between districts, so I'm not sure why th

The report you cite from the tax policy center indicates that 30% of variation in school funding is still within-state between districts, so I'm not sure why they feel comfortable asserting that "spending levels across districts have converged". The authors also point out that district-level funding analyses gloss over large spending disparities between schools within districts.