Their constitution and equivalent documents (Ontario and other commonwealth jurisdictions can lack a specific single document) do not imbue the government with the role or obligation to educate their population, the people have collectively reached moderate consensus that using a little bit of everyone's money to moderately educate a broader population is better than just wealthy people with less distractions educating their children in private institutions. This use of public money and implementation has nothing to do with the constitution, and so when challenged these institutions can often have rulings unrelated to academic merit despite existing for generations. Anyone (theoretically) could have always challenged but didn't.

If the people want the government to have specific education standards, then they need a much greater consensus to modify their constitutional framework to include that and its implementation.

Only spelling it out to remind people.