I always worry about my son on the school bus – he’s two, no seat belts! It’s a cultural thing. Here private ownership of vehicles is a relatively recent thing, and safety doesn’t seem to be such an issue. I always laugh at my friends who complain that I take my son out in the rain and cold, when they drive around with their toddlers in their laps.
If buses were to have belts, they should have full, proper seat belts as opposed to those lap belts. I assume lap belts are not as safe. @MacBean mentions his experience, but I’d love to see some research on the matter.