Home educated children are seen by health visitors, Dr's, dentists and have access to see the school nurse if need be.
Except for the ones who aren't, of course. The ones who are, are not the ones who need to be protected.
Most home educated children also go to things such as scouts, brownies, guides, Gymnastics, St John's Ambulance, Air Cadets, etc etc. Lots also pay for private tutors, for different subjects such as music, foreign languages etc. All of these are with leaders/tutors who have been DBS checked.
It's impossible to say "most" because there's no statistics and no data.
I'm sure the HE parents you know do those things, but that's classic confirmation bias. Those are the only HE parents you come into contact with are those actively involved in the HE community.
Having tutored HE children I know that there's a very tight HE community of parents who are incredibly dedicated to supporting their children's education and well-being, who have been badly failed by schools and LEAs. I completely support those parents and think they should have much better support and less judgement from authorities. It's terrible how badly HE parents are treated by the authorities.
But parents or guardians who deregister their children as a front for abuse, or because they simply can't be bothered sending their children to school, obviously they aren't going to be part of any wider HE community or in contact with other HE parents. They're not going to be sending their children to Brownies or tutors. They and their children are invisible.
I don't know how to reconcile better supporting HE parents who have been failed by schools and only want what's best for their children, with ensuring that abusive or neglectful parents can't simply deregister their children and vanish from sight. Personally I don't think DBS is the way forward, but there has to be something.