Look at the national teacher's organizations. Look at the curriculum. They've made themselves the enemy of parents who share my values. It may vary a tad from school to school, but it is way more widespread than you suggest. I wouldn't support them if the government didn't force me to.
My mother taught in public school, for a time, and most of my husband's family still does. The current principle at my old elementary school taught 5th grade when I was there. I know these people, and teachers, like people in any field, are all over the board on how good they are, but that's part of the learning too. I just don't buy into this paranoid view of public schools, but then I'm not on some of the fringes that don't want my child to learn about Darwin.
I think it's great when a parent who is home all day wants to homeschool, but in this case, it doesn't seem all that practical.