[throwawaystale]

My understanding is that there's a final "executive review", which is almost a rubber stamp, in that only one or a few percent are nixed at this level. In the early days, supposedly it was literally Sergei and Larry. These days, I imagine it's the head of the division in question, or perhaps one of their direct underlings. Or, perhaps, (plot twist), they pump the entire thing through an ML model. :-)

One thing I've learned in my (long) career is that wealthy companies don't really need to care about how much they burn during the hiring process. (For starters, your labor is free to them at this point.) That's just the way it is.