The problem I have with this is the "teacher" to "person" ratio. It doesn't matter if the teacher has more time per student to answer questions and properly explain if they don't know the answer. It's lacking in depth.
There really isn't any difficult material (at least in the UK) up to KS3. A competent tutor should be able to cover at least STEM alone, and I would be surprised if one person couldn't cover most of the rest.
There's also the issue that in a home schooling environment, the student is vastly freer to just ask questions. In a school, there's a curriculum and a lesson plan to follow, so the only questions that get answered are along the lines of "how do I do (this thing you just asked me to do)".
Another way to put that is that public schooling has the same problem, and institutionally at least the solution is to just discourage those questions.
It is not the concept knowledge that is lacking but the pedagogical knowledge. Knowing how to teach something is different from just knowing the thing. Especially when you consider that your child will have different learning needs than you did. Teaching professionals are experts at what they do.
A teacher has an entire classroom of children who rotate periodically, all of whom have different skills and learning styles.
A parent teaching their child for months and years gets a pretty good idea of how their child learns. They don't need to know how to accommodate every learning style, they just need to figure out one.
I don’t mean learning styles particular to students. I mean something specific to what is being taught: the dozens of different ways of teaching each skill.
This is quite an important point, though I would hope that someone who decides to dedicate 10 years or so of their life to the task would read up on the topic. (I mean that non-ironically, I suspect it is often lacking and doesn't happen.)
On the flipside, I have had several real teachers about whom I frequently wondered why they had chosen teaching as a profession. It was like they lacked both the aptitude for it, and had an intense dislike of students. To be fair, most were not like this, and there were a few truly excellent ones. But to make the argument that they are all highly trained, excellent professions is a bit of a stretch.
It's part of why teachers now generally stay in particular grade levels, rather than following the students or teaching multiple levels as was once standard. They become experts on the pedagogical content knowledge of their particular level, so they can apply years of experience to solving the unique challenges each kid has.
Most homeschoolers I know (I was homeschooled) would agree that its not for everyone. If you don't feel that you have the time or aptitude to teach then you should look for an alternative. Its a big commitment, both financially and in time spent.
That being said, you don't need to know all the material on day one. My mother did not know algebra when she taught it to my older brother the first time. She simply worked through the book a few lessons ahead of us, and if we ran into a problem we really couldn't answer, she reached out to friends and/or family who might be able to help. And I'm sure that wasn't the first or last time she encountered material that was new to her.
There are a significant number of resources and support organizations that can provide material, lesson plans, cooperative support, and many other things for those who aren't experts in a given field. I know many groups who collectively trade subjects leaning on friends who have a particular specialization.
If you teach your child how to learn on their own, they will be able to, at some point, take over their own education. That's what happen with myself and my two brothers. We all started taking primary responsibility for learning as we matured, and going into high school only occasionally leaned on our mom for assistance in a given subject.
The important thing here isn't that you as a parent know everything, but that you as a parent are willing to leverage the resources at your disposal and to invest time in learning when you need it.
Yes, I suspect this would depend quite a bit on both the quality of the parent as a teacher, as well as the "real" teacher we're comparing against. I've seen shocking extremes in either direction, for both individuals. I might be a bit biased in one direction, as my parents (and broader family in general) are quite knowledgeable, and could easily outdo the average teacher (as a broad average over the ones I encountered - full public school education in two different countries) on just about any topic, let alone their own areas of specialty.
