It would significantly expand taxes, and that nearly always faces stiff opposition with voters. Especially when it is an open-ended increase.
How exactly? Do you have any examples? Also, have you ever seen the price of car infrastructure? I would be willing to bet that denser walkable urban infrastructure projects are waaaaay cheaper than building and maintaining sprawling road, sewage, and power transmission networks. Sprawl is seriously draining the finances of many small cities and towns in the US. There's a whole book about it: https://www.google.com/search?q=strong+towns
You could also just watch this smug video https://youtu.be/7IsMeKl-Sv0
But, when it comes to schools, fewer buildings means lower costs. We've been suffering this for years, there aren't anywhere near as many schools in my district as there were 30 or 40 years ago, even as the number of students go up. It's less expensive to consolidate the schools into a fewer number of locations and increase the capacity of the remaining locations.
Ergo, going the other direction and creating more, smaller schools (each with their own infrastructure, custodians, some level of administration, etc) is going to require taxpayers to foot the bill. And not like a levy that only lasts for X years, but on an ongoing basis. Where I live (Oregon) there is massive resistance to new taxes. I do not think we are unique in that regard.