Anytime there is an accident like this, there should be a paper trial. But that is only if the bus driver know something had happened on the bus. If he is informed afterward, I am sure they had to write something up, stating what they saw or did.Yes, times have changed, but not to the point where negligence has to allow any kid in jeopardy. What's more, all public school employees are Mandatory Reporters. It is their job to note & report any evidence of abuse, and not just that of a sexual nature. And let's not fall back on that old chestnut that good help is hard to find. That's codswallop.
Mandatory reporter sounds good on paper, but in fact, really does not come into play that often in cases like this. You would have to prove that the driver knew it occurred or witnessed it, and did nothing about it. Without the recording it becomes a he said, she said type of deal and gets nowhere.