I am presuming that the school owns the laptops? At my school the parents/learners own the laptops, so there is no real issue with them taking them home. However, we do recommend that they have insurance.
If we were a school that owned the laptops, we would insist that parents have insurance and that they are responsible for damage/loss or theft.
The same way if somebody loses a library book, they would be expected to pay for a new one, or if I rented/hired a DVD from a shop, I would be expected to pay for a new one if it was lost or stolen.
I know this may be difficult with some parents in terms of money - but if the child wants the luxury of taking a laptop home, surely there should be a small fee attached to cover damage and insurance?
Please let me know if you have more questions.