The comparison is meaningless without knowing the needs of the two districts. Are the students in the thriftier district from wealthier households, for example, needing less support from school? Are there more ESL speakers in the costlier district? More students requiring special education? Are the buildings older, requiring more expensive upkeep? Some expenses don't break down to per-student or per-teacher. It's nice to say "trim costs and increase performance," but if a constellation of needs makes improved learning more costly in that context, you're stuck with it.