I wouldn't be surprised if the interview process for experienced engineers is unrefined.
At this point in Google's lifecycle most of the qualified, experienced engineers who would want to work at Google already do. There are orders of magnitude more new-grad engineers to interview and so it makes sense that they would lack the practice and refinement on those candidates, even if those are the most valuable candidates to hire. The recruiter might have just been confused and gave him the standard list for any "technical" job that they have to use for new-grads and so cannot ask things with nuance.
When I was an interviewer at Google it felt like 90%+ of interviews were with candidates who had less than four years of experience. Probably half were fresh out of college. After the fifth candidate in a row who can't do simple recursion or algorithmic analysis (and I mean simple) you get pretty discouraged. In one phone interview I got to interview an experienced engineer with over twenty years of experience in C. He completed the question I usually have to spend 45 minutes on with a new-grad in <10 minutes. It was probably my favorite interview of all time because I actually got to discuss the subtleties and he reaffirmed that I could maintain high standards.
Google is still a tiny company relative to the US economy. They might be slightly above average on some metrics, but that’s about it. Large enough they have plenty of idiots, small enough that most smart people don't work there.
As to high standards, you are testing for things that have very little to do with someone being good at the job. High arbitrary standards often remove the most talented people who generally don't have the same background as you.
EX: Suppose you where looking for a CEO, well having a collage degree seems like a reasonable requirement. However, a surprising number the best CEOs don't.
I'm a software engineer who really didn't know much about recursion or algorithmic analysis- I was a bio major/computer hacker. I did terrible on my first set of google interviews, at least on the algorithmic questions.
None of that was a reasonable predictor of my future performance at Google. You would have filtered out a perfectly good candidate (and this is, IMHO, the biggest issue is that Google rejects a number of people who would be great employees with its early filters). I can't say I have a better system.
The only interviews that made any sense for the time I got hired were the ones with the specific team members I was going to join. Once we got to chatting it was pretty clear I was a good technical fit for the team.
I still want to emphasize I don't have a solution to the high false negative rate in the pre-screening procecss.
When I was an interviewer at Google it felt like 90%+ of interviews were with candidates who had less than four years of experience. Probably half were fresh out of college. After the fifth candidate in a row who can't do simple recursion or algorithmic analysis (and I mean simple) you get pretty discouraged. In one phone interview I got to interview an experienced engineer with over twenty years of experience in C. He completed the question I usually have to spend 45 minutes on with a new-grad in <10 minutes. It was probably my favorite interview of all time because I actually got to discuss the subtleties and he reaffirmed that I could maintain high standards.