They're not required on school buses because buses are designed (poorly) to contain the children where they are, hence the close, high backed seats. Plus, children (like some adults) don't always do what's good for them so who's going to ensure 40 grammar school kids are buckled up? Maybe the fines from noncompliant seatbelt uses can pay for bus monitors. Massachusetts does not have a primary seatbelt law. Massachusetts is dead last in seatbelt compliance. How's that working out? EMT: "This guy's hurt pretty bad, but he wasn't wearing his seatbelt." Nurse: "Doctor, I know him. We must save him." Doctor: "Nurse, you know what it means. Under the new federal guidelines for triage care concerning automobile accident victims I cannot care for this gentleman because he violated section 31 paragraph 5, seatbelt compliance. Too bad. He should have eaten his peas. Dump him in the back with the old people."