I’m not sure Waymo pays much in taxes. Do they?

But in any event, cars and roads are massively subsidized, such that drivers get far more than they pay for. See for instance: https://www.cbo.gov/publication/59667

Roads are paid for out of the general fund, meaning that even those (few) who don’t use them pay for them, which I’d call a subsidy (as opposed to self-supporting). That’s not necessarily a bad thing; the same is true for many programs that support low-income people, and I think that’s great. But it’s still fair to call it a subsidy.