Well, just about any ML task needs people to prune and correct the training data.

I'm aware of moderation. What else?

Recaptcha is probably one you've actually interacted with, but even then you're mostly reinforcing existing predictions. But other applications within Google Maps are things like street number recognition, logo recognition, etc. Waymo contract out object detection from vehicle cameras and LIDAR point clouds. Google even sell a data labeling as a service.

I believe Google Maps has a lot of humans who tidy up the automated mapping algorithms (such as adjusting roads).

Annotation is time consuming and therefore extremely expensive if you have a $100k engineer doing it.

https://www.forbes.com/sites/korihale/2019/05/28/google-micr...

Yes you can report problems with the road network and people update GMaps manually. And up until a couple of years ago users could do it themselves, but they took it down for some reason.

Changes to other types of places can still be done manually by GMaps users themselves, and other users can evaluate that, and I guess if it's a "controversial" (low rep user did the change or people voted against it) a Google employee evaluates it. And if you're beyond certain level as a GMaps user you can get most changes published immediately.