Why would our Bais Yaakov & Yeshiva educated parents be unable to teach elementary school topics? Doesn’t that say something about our Mosdos?
We’re getting pretty far down into the weeds here, but no, it does not.
1.) Not all parents sending their children to Yeshivos or Bais Yaakov schools themselves went to such schools (e.g., BTs, converts). These parents might have a harder time teaching some limudei kodesh subjects to their children that they want them to learn.
2.) Even if a parent has great knowledge of the subject material, the ability to effectively impart this knowledge to children (e.g., curriculum development, teaching strategies, etc.) is another skill entirely.
Also, with terribly inflated housing costs, many families struggle with a single income even when sending no children to private school. Moving to a suburban or rural environment would possibly bring those housing costs down, but would also potentially bring the available income down as well.
I don’t mean to say with these responses that I disagree with you regarding homeschooling or other alternatives/supplements such as part-time/co-ops, on the contrary, I think it’s a great idea. I just don’t think that, given the current state of affairs, it is feasible to go on a Khmer Rouge style social re-engineering kick by forcing children whose parents cannot pay the full tuition out of the schools. A better infrastructure to support homeschooling needs to be put into place. American culture in general is not geared towards homeschooling (or parental attachment to their children in general), but hopefully as more and more parents home school, there will be some favorable cultural changes (e.g., more flexible work schedules, better part time jobs).