If someone is abusing children, turn them in and let a judge and jury decide.
The public school bureaucrats are already biased and have their own preferences concerning homeschoolers. They are not objective.
Teachers are designated reporters -- if they see something off, they have to report it.
If parents isolate kids from the outside community -- it does happen -- how do you catch 'em?
That's not the way it works. I'd tell you, but it's really depressing.