It sounds like your understanding of racism is not very nuanced. Explicit statements of racial hatred are the most obvious kind of racism. But that's not where it ends.

For example, consider the study "Are Emily and Greg More Employable than Lakisha and Jamal?" [1] They found that resumes with black-sounding names were less employable than the same resumes with white-sounding names. Is that because a large number of hiring managers are also KKK members who put on their hoods before sorting applications? Probably not.

A more likely explanation is that, as Harvard's Project Implicit [2] demonstrates, a lot of people are consciously anti-racist but still have racist attitudes and reactions. If you live in a segregated society, it need not even be a bias against blacks, so much as a bias for people who are more familiar to you. Is that effectively racism? If I were somebody not getting hired because of the color of my skin, I'd sure think so.

So in the case of Google Plus, I doubt the mainly white, mainly male, mainly millionaires sitting in a suburban office park were consciously saying, "At last, our revenge for Custer!" But them saying, "Looks good to us!" and then enforcing it is effectively saying, "We believe our personal biases and local cultural norms are good enough for the entire world." That might not be explicitly racist in intention. But I don't think that's required to create a racist system.

[1] http://www.nber.org/papers/w9873 [2] https://www.projectimplicit.net/index.html