The philosophy is, our kids are too good to go to public school, but we don't want to homeschool them, so we'll just take government money away from the real schools and set up happy little palaces of keeping the riff raff, or anyone we don't like, at a safe and unviewable distance, and train them to believe everything we tell them. And let's not use actual credible teachers who have gone through silly things like college, and have unbiased knowledge, or use any standard curriculum. Okay, of course that's not always true; there's even a charter school in my town where I once had friends who attended, and is a pretty cool place. It's a good concept, I guess, where you could in theory create a less regulated learning experience for younger kids. However, it's most often abused by the fuckers descirbed above.