No, I don't believe that is very realistic. It isn't required to have flextime like it isn't required to have children. If you have kids, there are buses, carpools, and other ways of transportation to allow you to work during school hours. It would be a luxury to have flextime, but it wouldn't be realistic to the business. If you are part of a business team then you are needed when everyone else is needed.
Many parents don't have time to help their kids study for school and even if they do, they may not remember the material well enough to comfortably teach it to their children. In Palm Beach County, we are fortunate enough to have teacher led after school tutoring sessions available for each learning department. Even as a single parent, you can still help your kids get the help they need by taking advantage of this resource. For a small fee, there are also students available for one-on-one tutoring.
I was put in a C rated high school my freshman year, and because of the rating parents would say how bad the school and kids were that attended. While I was there I had four of my favorite teachers and made my best friend. Just because the schools ratings are based on a test doesn't mean that the school is bad. I am a straight A student yet has bad test anxiety and do poorly on the FCAT. Standardize testing is not the way to judge a school, the students, and teachers.