No different than how H1B's are implemented, you'll see a "no automated cars for hire" law, if necessary it'll happen city by city if the political will isn't there Federally. It will be a very specific proscription, likely very industry specific, because only a large number of impacted workers will have the political clout to establish such laws. And it might even be only city by city, rather than at a Federal level.

There are ways in which H1B is imperfect, doesn't work, and isn't fair. There will be ways in which making automated cars for hire illegal will be imperfect, doesn't work, and isn't fair. But those attributes haven't driven the former into the dustbin yet. If anything it's about to get stronger under the current political climate, so there's no reason to think the later won't be successful, at the least as a delay tactic so that automation isn't as disruptive as hypothesized.

Also, as a country establishes a more isolationist attitude, it matters less what the rest of the world does, and the rhetoric right now is distinctly a more isolationist attitude.