I work at Google as an SRE, joined a few years ago. I am approaching 40, worked in a bunch of other companies before. My degree is is in the humanities, from a third world university you never heard of. I don't have any open source contributions. I speak lousy accented English (but I am a man and "white" if we are counting privileges.)

I got contacted by a recruiter. I had a couple of phone interviews which felt like sanity checking that I knew what I claimed to know. I was asked to grade myself in a bunch of areas. I chose makes around 5-6 for the stuff I think I know well, and zero or one for the rest. I was given some recommended reading list that I ignored. I did browse Skiena's book on algorithms to get in the zone. I didn't study it or implement anything. I am very stressed during interviews and would forget anything that isn't in long-term memory already so there was no point. (know yourself...)

I went to the onsite interview. Year, it's ~5 hours of being interviewed by people who have done dozens of interviews before. Everybody was unfailingly nice. I was panicing, not because "omg Google" but "omg humans I don't know for years already". Some algorithms, some Python, more troubleshooting and Unix. I had to estimate some numbers, so I announced I would use my cell phone calculator to not get anything wrong. I multiplied even low numbers by two on the calculator. Most interviewers are poker-faced about whether they liked the interview or not (now that I am an interviewer I understand - they probably try to put some distance between the interview and their rating, as they should). I could see that one was happy. I could see that one was not.

I was hired. Large team, three sites. I did a reasonable amount of C++ (not a language I ever claimed to know) fixing bugs and performance issues. Most of my work has to do with low-level synchronization in x86 - I picked a small "specialty" first and applied it to a number of problems. I like it. I feel that I actually write more code than my peers in the product teams, as they do too much design-docing, design-reviewing, meeting, etc. (they are SWEs, I am a SE). The design doc culture at Google is excessive and silly. I am exposed to that too.

I earn slightly more than my similarly-leveled peers on the SWE side /before/ accounting for oncall. Oncall rarely pages on weekends. I feel very able to fix any problem while oncall, or to escalate if not in my area. It doesn't stress me. I mostly consider it free money.

My peer SREs actually know far more about all the nice Google architectural stuff than our peers in SWE-land, who are mostly implementing features on top of huge abstraction layers and typically are only exposed to one particular facet of the infrastructure. Google's infrastructure is impressive and something of a marvel. It doesn't mean it's perfect. SRE is the better point of view to observe it.

Google employees are better than in any other large company (a few boutique shops are better on average, of course, at a smaller scale). Some of them like to pretend that they are better than they are to the outside world. Internally, nobody goes far being arrogant, and showing vulnerability or gaps in knowledge is not a problem. There is also someone smarter and nicer than you anyway.

I interview people. The immense majority of people I interview are really good. It's not possible to get to the point of onsite interviews unless you are good, you just know the person you are talking to is a potential peer. Interviewers are happy when their candidates do well. The committee ends up rejecting most, though, out of hyper-conservatism. I have no idea how I was hired. I suspect there is a large amount of randomness between "invited for an onsite" and "hired".