Spicerack -There are several interesting aspects to your response.
The first is your perception that a child is 'upping the ante' as you put it. That is an adult perspective, and has no place in this situation because, as I and others keep stating, and you and others keep ignoring, this was a CHILD - they don't think and act and 'up the ante' as adults do.
The second is your willingness to shelve your frequently stated dislike of Muslims and their ways of life, in order to twist yourself in knots to defend this bus driver.
You said - // The driver's culture (probably Muslim) still deals with cheeky kids the way we did throughout history until, what, the 1980's.
You don't seriously expect third worlders, which some insist on flooding the west with, to be 'up to speed' with our fantastic PC culture? //
This would be laughable were it not so serious. With no evidence whatsoever, you are attributing a religion to this driver to allow him the backward attitudes of his imagined faith towards discipline of children, and then use that to defend his behaviour! I have read some people twisting themselves backwards to defend this man, but honestly, that is as inventive as it is ridiculous.
Then there is your use of the phrase - ' … if you are a woman or a wimp ...' which implies that you see little difference between the two, but it also implies that a degree of machismo and 'telling it like it is' is required to deal with this incidents.
You appear to view any stupid behaviour as needing direct action from you - you could only hear yourself be abused by the other party if you got out of your car to 'deal with them' - as you clearly feel is he right way to address such situations.
Getting out of your car to shout at a stranger is never a good idea - at best it starts a pointless shouting match while you either decide which of you two men is 'harder' or you see how much you can frighten and intimidate a woman or a child.
But maybe you should think about this when you are busy righting the wrongs on the road as you clearly feel you must - you never know who is going to get out of the other car. They may have just as big a sense of entitlement as you, they may be willing to shout as loud as you, and maybe, just maybe, they are willing to make their point a little more forcefully than you -
https://www.theguardian.com/uk/2000/apr/14/marktran1