> I've heard stories that at Google, the non-engineering workers at campus may not socialize with engineers at all.

I worked at HQ as an engineer, and didn't notice any such thing.

Most of the time I probably didn't say hi to cleaning staff, for the same reason I wouldn't say hi to most of the people I pass by in the office: because they weren't someone I knew. Of course this might vary depending on context, but I was treating them the same way I treated everyone else, or at least trying to.

Do other people say hi to every single person you see in the building every day?