the point is that if you are interviewing 30 people for every hire you are spending way too much time and effort on interviewing. if you had better recruiting funnels you could easily get down to 2 or 3 interviews per hire

I'm not so sure. My understanding is the big tech companies hire engineers on a rolling basis and basically take everyone they like.

They're not approaching it for the frame of satisfying a requisition for a specific role with the best of the N applicants for it on X date, they're picking up talent as quickly as possible and then sorting out where to place people after the hire/no-hire decision is made.

It's more like there is unlimited demand, and most managers could think of more things to do if they had more staff.

If this were the case, there would not be so much whining from these same companies about talent shortages.