An interesting stat about school buses is that over the last 20 years or so, there has been a roughly equal number of bus driver deaths and passenger deaths. Since a school bus typically carries a much larger number of passengers (as many as 70 or more) than drivers (1), this means that the risk of death for the driver is far higher than that for the passengers (although exactly how much riskier it is is difficult to determine from the published data).

Another interesting safety feature of school buses is that the bus bodies are clipped to the chassis rails rather than being bolted or welded to them and thus are held in place solely by friction. This is so that the bus body can slide forward a couple of feet along the rails in the event of a head-on collision, which greatly reduces the deceleration forces experienced by the passengers (this crash test video shows the phenomenon clearly). This does not help the driver much either as they're sliding forward into the engine compartment or into the oncoming vehicle in the case of flat-front buses.

It’s pretty unlikely that the bus would roll

Yeah, buses really aren't going to roll unless they get hit hard on the side by an equally-large vehicle traveling at a high speed - or unless they run afoul of some mythbusters.