Sidewalk Labs is one of the most ambitious ventures within Alphabet, and Google has always had a hand in humanitarian efforts, up to and including government. Thus, it only makes sense that The Guardian, managed to get their hands on some messages and documentation that indicate that Sidewalk Labs is planning a to support public transit in the United States. Details that weren't released to the public via official channels went to every city in the Smart City contest held by Sidewalk Labs, with an offer going to Columbus, Ohio, the winning city; Sidewalk Labs offered to help support public transportation and public matters related to private transport in the city.
For starters, Sidewalk Labs wants to offer cities Flow, a traffic analytics utility that leverages Google's mapping data and expertise to help extract meaningful traffic data and work out the best ways to route traffic and fixes that could be applied to fix traffic jams. Sidewalk Labs' overarching vision, should the city choose to let them fulfill it, is a bit more comprehensive and invasive. Public parking would be brought into the modern day with new signage and the like, easing up on the 30% or so of city traffic, according to studies, that's generated by people seeking parking. Cities would stop using whatever proprietary payment systems they may have and begin using Sidewalk Labs' own payment system. A more heavy-handed tactic would include heavier reliance on ride-sharing services like Uber, offering subsidies to get lower-income citizens on the go via those services.
The large number of fixes, tweaks and outright revolutions to public transit proposed by Sidewalk Labs would be a tough pill for some cities to swallow, but those with an interest in modernizing or whose current transit systems are a bit on the inadequate side for their citizens' needs will likely jump on board at some point. As open as they were to the Smart City program, word from Columbus on whether they plan to accept Sidewalk Labs' offer has not surfaced yet. The documents and messages centering around the transport takeover are available via public records requests by law, but have not been officially released by Sidewalk Labs.