OSM is for nerds. Very hard to add even basic info. Google Maps it’s trivial.
Same as uploading photo to Google Maps is easier than adding it to WikiMedia Commons. Such is life.
(Ironically one of the biggest sources of photos is commons is Panoramio; before Google merged it with Google Maps, the photos there defaulted to Creative Commons.)
To add new features I have to use SCEE, which is more nerdy mainly because it involves using FDroid to install it. But I've no idea how to add, say a park bench to Google Maps.
On desktop, right click on the map and choose "Add a missing place." On mobile, long-press to drop a pin, then scroll down to "Add a missing place."
Does OSM require installing a parallel app store to add a park bench? Sounds like a UX-killer :/
You're right though, installing another app store is a non starter.
Google probably sees their data as a moat and likely aren't interested in two-way data sharing. (Given how many of their competitors are now involved directly or indirectly with OSM or Overture, they may be correct.) OSM probably can't legally scrape it without an agreement in place.