It's interesting that there exist these "moats" in Google Maps. When I thought about it for a moment, it actually is unsurprising to me, and I'm pretty sure that the reason is actually due to an implicit bias. Things might be changing, but I think that most of your typical smartphone users have historically been affluent white (males?). Because most of the information for Google Maps come from Android users. And where do they typically go? To the same places that other affluent white people go.
I doubt there was anything intentional about this - it was probably just some Google engineer looking at the data that they had and then building some tool. But why would they even consider race?
Question your assumptions, and when you build tools based on data, think about the data. Why does it look like it does? It's hard to see your biases, though.