Google doesn't really optimize to show you ads. They're a monopoly and the voting shares are owned by Larry/Sergey; they have no intrinsic motivation to care about anything. If you want to be optimization-brained (don't, it's bad for you) they optimize for metrics that individual people make up and use to get promoted.

They monetize the map other ways, like with the expensive API fees, but I wonder if they really care about it. Whenever I look at it for a few seconds I see something obviously sloppy, like misspelled POI names or people adding fake businesses at their apartment.