Will most human drivers?
I've been driving a long time. I rarely see people hit their brakes when a ball comes out, or even slow down. My anecdotal evidence from 300,000 miles of driving says this isn't the case.
Every individual human would need to learn this separately from experience, which would require far more soccer balls (and children).
The problem with people is distraction. The problem with code (AI-ish) is people.
The conclusion that a neural network classifies stuff 'correctly forever' is also not one supported by the current state of computer vision.
So the situation is really much worse than you describe. Even if we invested in demonstrating the "soccer ball and child" scenario for all driving students, they wouldn't be able to apply the experience to tennis balls and dogs, or a child entering the road without any sort of ball. Teaching people to drive would require an exhaustive course in every conceivable scenario that might arise while driving. You can see why it's an intractable problem.
As for the second one, looks like the other car just passed in front of it.