That’s only true in the short to medium term, and it’s usually less impactful than many opponents claim. Longer term, new schools will be built less often, so it all largely comes out in the wash and isn’t much different vs new school construction.

One thing that’s interesting is that charter schools receive significantly less funding per student on average vs public schools (biased source, but the numbers should be trustworthy). That reduced funding is due to the reduced requirements on charter schools, such as no buses or special needs programs. At least in theory, traditional public and charter schools are on even footing per student. Charter schools also often factor in some level of profit since they’re generally run by private orgs, so they tend to be a bit more efficient at dollars spent vs learning outcomes (e.g. our charter school is in a nondescript office building, our public school building is bespoke and takes up ~2x the space per student). Public schools have no such profit motive, so they can be a bit less careful with their budgets. That doesn’t directly impact students or taxpayers, but it does show that public schools may have some fat to trim, so the short and medium term impact is often less than you’d otherwise expect for a funding cut.

I think both sides of this argument misrepresent the facts. Charter schools aren’t perfect, but they also aren’t the drag on public school funding opponents claim.