Are they? I get the impression that only consumer-facing stuff is Google, to give people a familiar color scheme¹ as well as allow terribly formatted search queries to still work (if google can do one thing it's search). However, anything using geo data in a back-end fashion seems about evenly split between government base maps, OpenStreetMap, and a collection of misc providers that Google is one of
¹ conversely, I struggle to find my home town on Google Maps. It's all about vague, washed-out shapes, besides the bright shop icons and, nowadays, advertising pins. It's a matter of what you're used to so I can very much understand that the average consumer, who's less familiar with maps than me, is totally lost when getting Carto as a map
Full list: https://wiki.openstreetmap.org/wiki/Organised_Editing/Activi...
It's more surprising at this point that Google isn't getting in on the fun, at least taking the good bits and calling their own data a 'separate layer' so they don't have to contribute anything back. (And of course no Chinese companies, since accurate maps are illegal there: https://en.wikipedia.org/wiki/Restrictions_on_geographic_dat...)