I've been following this and I have a few more thoughts on the matter.
First, is that an advanced degree and/or teaching certificate does not make you a teacher. According to Merriam-Webster, a teacher is "one that teaches", with teach being defined as "to guide the studies of" and "to impart knowledge of". The advanced degree and/or teaching certificate are pieces of paper that state that you have knowledge of things that were taught in the education program that you attended. Does that mean that you had more history classes, science classes, math classes, english classes, spelling classes, etc. since those are the types of topics that are taught in school? Or was the majority of the classes about the theories of teaching, classroom management skills, etc.? I know when I got my advanced degree in accounting that college had only prepared me for the theory of what accounting was like. I had to go out in the real world to obtain the skills necessary to actually become an accountant.
Second, I have been a teacher. Anything that I have knowledge of can be imparted to others. I taught my child to speak, what colors were called, how to order when at a restaurant, manners, etc. I have also been fortunate enough to teach other kids things regarding nature and the natural world because I am a naturalist. I've taught school groups, homeschool groups, co-ops, and summer camps how to identify animal tracks, how to identify plants, water cycles, seasons, etc. Does it matter that I didn't have a teaching certificate? Obviously not to the parents of the kids who paid for their kids to attend a class taught by me.
Third, I outsource teaching in my own homeschool. I don't know that much about taekwondo, but I found someone who does. I'm not much of an artist, but there are classes locally that my son loves to attend. I'm not so good at identifying rocks, but my brother-in-law is amazing so he is helping my son. My son has attended numerous classes at zoo, museums, nature centers, etc. all taught by people that didn't have teaching certificates. Yet, he still managed to learn.
In summary, please realize that there is more learning going on in the world than that just taught by certified teachers. Anyone can have knowledge of a topic and pass that information on, that person is the teacher and you would be their student. The other part is that you, yourself, can always gain more knowledge. And here's a hint: the authors of books are teachers; they have put their knowledge in a form which you can read and learn from. And, no, most of them are not certified teachers either.
I agree that education is important. I think it is so important that I am homeschooling my own child because I don't feel that public schools are that concerned with education, as much as they are concerned with teaching kids to take tests. I take this responsibility seriously. I study various standards for each grade level (the east coast schools have much higher standards than others that I have seen.) I spend hours and hours taking those standards and putting together curriculums that will meet those standards, all while adjusting the lessons so that I can take advantage of how my child learns. Then I spend more time doing the actual teaching. I don't teach to a test. I teach for life. And every other homeschooler whom I know is just as dedicated to providing the best for their children.
I totally disagree with Andrew's solutions. Testing a homeschooled child 4 times a year - why more times than a public schooled student? As far as I know, public schooled kids in my state only have to take a standardized test once every other year. Getting consent from a 12-year-old to be homeschooled - do you also require public schooled kids to sign a form stating that they want to be taught at the public schools? And allowing the state to decide which books I can and can't use - because the books the use in public schools are so good at teaching kids? If that was the case then why do we have so many public schooled kids failing the standardized tests?
I guess it bothers me that people who support a failing system, such as our current educational system, want to make extreme generalizations about something they don't understand and then want to tell everyone what's wrong with it and how to fix it. Go spend your time trying to fix the system that you believe in. Those of us in the homeschooling communities are busy making the best of the systems that we have already in place and working towards changes that would benefit all homeschoolers.