How does Google Maps get the location of drivers?

I see that Google Maps recently redesigned it's Uber integration.
And as far as I can tell the Uber Riders REST API doesn't have an API endpoint to get the nearby locations of the drivers around the pickup user location.
Can anyone explain how the location is determined?

Solution

"And as far as I can tell the Uber Riders REST API doesn't have an API endpoint to get the nearby locations of the drivers around the pickup user location."

This is correct- there is no public nor privately available API endpoint showing location of nearby drivers. Google are estimating it based on ETA.