Interestingly, lal123, that was one of the central lynchpins of the (now utterly discredited) Badman report on Home Education. The NSPCC was very keen to promote the same line, probably with a view to gaining the contract to provide a wellbeing inspection service.
Your statement assumes that schools do indeed pick up on child protection issues more reliably than neighbours, relations, friends, supermarket checkout staff, GPs, anyone else that children come into contact with. Is it true? If not, then there are serious problems with singling out as being perceived to be at particular risk those children whose only differentiation from the general population is that they don't go to school.
Please remember that people who are determined to abuse their children will do so. If that requires them to have unassisted childbirth, never register the child, never register with a GP, move frequently, whatever the hell it is, you can be sure that they will do whatever it takes to stay under the radar.
Claiming that one sector of society should be singled out for particular scrutiny - particularly given the number of false positives, and the emotional damage done to an innocent family by a SS investigation, even if they are vindicated - is highly offensive. More girls of Asian origin are forced into marriage. Should we interview all Asian families when their daughters become 10, just in case, and take further action if they do indeed come from a culture in which arranged marriage is the norm? [spot the straw man argument, but I hope the point is still made]
If this seems an overly aggressive response, then I apologise. Many of us in the HE community spent about 18 months leading up to the last general election putting a huge amount of our energy in fighting a change in the law that was based on Home Education = abuse fearmongering by those with a huge amount to gain from interfering in the lives of innocent families ("rentseekers")