Maybe they have the same parser in the validator and the real driver, but the vagaries of the C language mean that when undefined behavior is encountered, it may crash or it may work just by chance.
I understand what you're saying. But ~8.5 million machines in 78 minutes isn't a fluke caused by undefined behavior. All signs so far indicate that they would have caught this if they'd had even a modest test fleet. Setting aside the ways they could have prevented it before it reaching that point.
That's besides the point. Of course they need a test fleet. But in the absence of that, there's a very real chance that the existing bug triggered on customer machines but not their validator. This thread is speculating on the reason why their existing validation didn't catch this issue.
