The internet contains more than just information. The student can stumble upon inappropriate content on the internet, same as they can at home, and the parents can do nothing to stop it from happening. If parents know that their child will not use the computer effectively, they can deny them permission and avoid an incident. Also, if the computer gets broken, the parent of the child can be charged.
School property can be used by everybody in the school, making it public property. This means that students must have permission from their parents to allow them to get access to public property.If the student breaks something that is owned by the school, then the parents can be held responsible.
Any more than for access to knowledge of any other kind.