The social interaction dynamics that happens at the Google building is a reflection of society at large. As another example, I've worked at the offices of charity institutions where the higher level white collar workers ignore the cleaning people. The common theme is that humans in general (and not Google employees specifically) like to stratify people.

I recently flipped through a high school yearbook (these books were more popular before the era of Facebook) and noticed that the cafeteria ladies were relegated to a tiny group photo. However, the teachers got individual portraits. So a public institution funded by taxpayer money implicitly stratified 2 different types of workers. Each page of printing a hardcopy yearbook costs money and the food workers are not the same value to the yearbook staff. See the common pattern across humanity?