That's not true at all. You should look up the top spending per capita (large)[0] public school districts and you will find NYPS, LAUSD, CPS, and Baltimore school districts among them.
[0] there are lots of high-spending small outliers serving areas with total (adult+child) populations in the < 100k range
[0] there are lots of high-spending small outliers serving areas with total (adult+child) populations in the < 100k range