From what I understand the driver can take control even in this self drive mode. Presumably the driver wasn’t paying any attention. I would have taken a license number and notified the police that the vehicle drove by a stopped school bus. I’m sure the bus driver would corroborate the incident.
I recently had an Uber ride as a passenger in a self driving Tesla. I could clearly see the very large screen. It was amazing. The Driver explained a lot about the many cameras which was very interesting.
IIRC he said that there was one camera looking at him and if he looked down for too long (a very few seconds) he got notified somehow. I forget if it was an alarm or what. Perhaps one of the Tesla owners on this thread can explain that.