Maybe this will create the voting bloc needed to get charter- and voucher-based schools off the ground, and out of the hands of unions. Public-sector monopolies don't have a great track record.
The track record of charter- and voucher-based schools is not better than that of public schools. In some cases, like online charters, it is far worse.
Charter school teachers can and do unionize. ("When charter schools unionize, students learn more, study finds" - https://www.chalkbeat.org/2017/9/25/21100993/when-charter-sc... ).
Education leans towards being a natural monopoly because of the good economy of scale. It is cheaper to run a large high school than a many smaller schools, and that larger school can offer a wider diversity of courses, making it a broader match to the community's needs. A larger school system can also share administrative costs, have a permanent substitute teacher pool, etc.
I don't see how charter- and voucher-based schools change that calculus, which means they will merge.
Private sector monopolies have an even worse track record than public-sector monopolies like the USPS has for local mail delivery.
I’d suggest wondering why this isn’t the case in the US, and fix that instead.
It's the private sector completing these jobs, not government employees. Those jobs are routinely bid out to contractors, who complete the job with a profit margin.
It's both sides of the coin coupled with a relentless need to profit off everything possible at every opportunity.
They're government projects. The details of how they staff them are part of "why is the gov't so incompetent" question. Comparable-scale private projects don't exhibit the same horrendous inefficiency relative to other countries: Apple's $256B of spending per year isn't a large multiple as inefficient as Samsung.
As far as the reason, people have been trying to take a rigorous look for years and years and have come up with every reason under the sun, spanning the political spectrum: onerous environmental review, lack of nationalized benefits pushing into labor costs, unproductive construction unions, lack of oversight of private contractors, etc etc etc etc.
But since the blame is bipartisan, our political culture doesn't know how to handle it. There's no constituency for basic competency in government if it can't be monocausally forced into the box of an existing generic political slapfight (as in your comment).
Literally Apple's HQ was $2 billion over budget. Private enterprise has these exact same problems. Government isn't any more or less incompetent than your average US business, unless you completely ignore how your average business operates.