This might be implemented with the same feature as the lack of clusters: a label suppresses other labels around it, with bigger cities suppressing more. Would be easy to do with a greedy algorithm.

It's not the implementation that surprises me - once I know it's the right thing to do, I can easily figure out a method how. What's surprising is the insight that it is the right thing to do.

I think the parent was suggesting the intuition may have come from applying the other more obvious algorithm.

My guess is that it may be the practice used since years by designers of printed maps, ang Google has just consulted the right people on the topic.

Agreed, I wasn't trying to say it was hard. Mostly pointing out how two features could be the same simple mechanism.

I wonder if it's really a genuine idea or simply the unintended consequence of an algorithm.