>Public transportation service means the operation of a vehicle that provides general or special service to the public on a regular and continuing basis consistent with 49 U.S.C. Chapter 53.

From the FTA. and for those who really want to dive into the law of it: https://www.law.cornell.edu/uscode/text/49/subtitle-III/chap..., whose own definition is:

>(A) means regular, continuing shared-ride surface transportation services that are open to the general public or open to a segment of the general public defined by age, disability, or low income; and

in a legal sense, Waymo doesn't seem to meet even these high level definitions. So it's likely classified as private transportation unless I'm missing something.