The driver returned to the scene and owned up. She was probably in shock from the collision – callous and selfish – maybe, but people act in stange ways.
There is nothing to suggest she had tried to evade justice or was responsible for the collision.
She acted incorrectly, yes, and is rightly punished for that.
Baldy tyre – not good, but would it have made any difference.
Specualtion will not help here, neither will castigating the driver.
Very sad outcome all round.