This is nonsense. Google has more than enough legal resources to handle this. So much so that it would be nothing more than a regular 3-6 month project that would be assigned a small team of lawyers inside their org. It's no different than any other regionally-regulated product launch at large companies.
Not only that but Google has enough money that they could just hire away some folks that work at Uber/Lyft to get a huge jumpstart on any such project. Even if they didn't need such expertise they'd probably still recruit and hire those people just to be safe; to get the perspective of people with experience.
Big companies have big legal organizations and they don't actually operate that differently from the IT orgs that so many of us on HN are used to. For example, they would probably divide up the task on state-by-state basis with lawyers certified to practice law in each respective state assigned as SMEs or to-be-SMEs. They would do their research and for bigger states they might even have county-level SME lawyers or at the very least paralegals that focus on that particular region. Big cities would probably be assigned their own teams of SME lawyers as well.
It's like any given complex programming task: Divide and conquer. Rolling out a new highly-regulated product across a large region is a highly parallelizeable procedure.