Homeschooling requires some degree of investment in the child, even just to keep them occupied or tolerate their presence. School provides free childcare for long periods of time. I don't think the majority of abusive parents will ever homeschool their children, because most are not believers in teaching an abusive ideology but rather have simple personality disorders. "Homeschool makes it easier to hide abuse" presupposes that abusive parents are planning or organizing abuse which is plainly not true in the majority of cases.
Like the Satanism panics of the 1990s demonstrate, elaborate imaginings of complex sadistic rituals that are necessarily rare[0] bordering on nonexistent, tend to capture the public mind and suck oxygen away from treating the totally unattractive (not even in the capacity of making for a true crime special) real problems.
If you want to see this on TV, the last season of The Wire was about it.
[0] There were actually a spate of ritual killings in Liberia through the 1970s, proving humanity capable at least and making the issue to be one of reasonableness.