Another thing that isn't transparent to outsiders is how frequently candidates are shopped around if it becomes obvious they aren't a great fit for the role the

Another thing that isn't transparent to outsiders is how frequently candidates are shopped around if it becomes obvious they aren't a great fit for the role they were recruited against. I can't tell you how many times I've been asked if I'm interested in candidates that started out as SRE, CE, PM, or other roles. As mentioned, recruiters are paid on hire rate, and it's in their interest to ensure that strong Google candidates are identified and presented to as many potential hiring managers as practical. Additionally, it's common for interviewers to interview for multiple different groups (as an additional tech interviewer, a xfn interviewer, a Googleyness interviewer, etc), so exposure to job requirements can be reasonably broad at the interviewer level. As I imagine many suspect, calibrating interviewers is hard, and always has been, for a company hiring roughly 10,000 people every year.