As someone else said, Google shares something similar with cities via the Waze Connected Citizen Program[0][1]. Waze publishes a list of cities that participate here[2].
I think Google can't share the traffic data it shows users as it's probably an aggregation of multiple sources, and they probably don't have the rights give away that information. The Waze CCP is an opt-in service on Waze where people can share their information and input with cities.