I would be surprised if a school bus driver normally has an awareness of exactly which kids are on the bus, unless it's a special ed bus or some other special situation. During the periods of my life when I rode any sort of school bus, the only ones where I think the driver would have been fully aware of exactly who was on the bus were both very atypical. One was a private school (in the US) that had teachers at the school serving as drivers, providing pick-up within sight of each child's front door, and driving vans rather than buses, because they were only transporting children who lived more or less on the teacher/driver's way to and from school, and the absence of any child would definitely have changed the route for that particular trip. The other was when I was attending a private school in a foreign country, where I was the very young child of a diplomat, and there were significant security concerns surrounding the issue of my riding the school bus -- the bus's entire route was designed to pick me up last in the morning and drop me off first in the afternoon (which I eventually learned involved going *way* of its normal route), to minimize the amount of time and distance that I was exposed to any risk (which could have posed a risk to the other children too). In that case, I'm sure the driver always knew whether or not *I* was on the bus, but not at all sure he would have known whether any particular one of the other kids were absent on a given day.
But for an ordinary everyday school bus route, with regular kids? Especially for the going-home leg of the trip, I would expect that a mob of kids just pile onto the bus in the afternoon, with teachers of the younger grades making sure each of the younger children gets on the bus if they're supposed to, and the driver simply leaving at the appointed time and stopping everywhere he normally stops unless someone specifically alerts him that a child who is the only one who gets off at a particular stop is absent that day. And even if this driver had been under the impression that Kyron wasn't on the bus that afternoon, I'm sure that when he saw a familiar parent waiting at the stop, he would stopped, thinking either that either he'd been mistaken in believing the child wasn't on board, or that the parent needed to tell him something.
