When the new people are actually living in the area and paying property taxes, then there will be enough money to build new schools, pave roads, etc. There's a delay in other words.
But why?
None of this should be unexpected. All construction requires permits so you know ahead of time what's being built and almost certainly can just extrapolate out how many new kids will be in the school system based on the current rates.
It's like how a bunch of cities approve new commercial construction but then don't also don't fast-track some residential construction; you're just going to generate traffic because nobody can live close to work.
Municipal bonds are meant to address this. The city can borrow against that future tax revenue to build infrastructure today.