One of the reasons they love the Chrome system rather than a more traditional install (be it Linux or Windows), is when some clueless student comes in saying: "it broken," the staff can wipe the device clean in a second. The student can log back into the Google services to bring their account back, and they minimize undue downtime to repair software problems created by the students.
Could you get something similar going under an alternative distribution, sure, but with this they're is no labor/cost overhead associated with maintaining the server systems and software.