

You forgot about the fact that buses have bigger windows and the passengers inside them, kids in this case, have smaller mass. Therefore I would argue that the chances of ejection are not less than a typical car.
Plus, pretty sure those old big muscle cars and luxury cars had more mass than a typical family hatchback and guess why we still got seatbelts?
Makes me wonder, what if they just let it sit for another 20 years and then recapture the helium to sell it or something?