>and the carriage drivers could become chauffeurs
And the people in Detroit could move somewhere with productive economic activity. Why are they different from carriage drivers?
FWIW I used to be a protectionist. I became disillusioned with it when the choices around which things to protect, what to protect them from (foreign competition vs. automation), which status quo to lock in, and where we draw the boundaries of units that ought to be protected from each other, started to seem arbitrary.
I remember a particularly compelling line of argument from an economics textbook: okay, the US should make its own cars, but why stop at the national border? Why not have every state make its own cars? Think of all the jobs that would create! An auto industry in every state! But why stop at state? Why not make people sell their cars and trade to locally manufactured ones at every county line? Because it'd be a huge waste.
And, of course, many of the things we propose to protect "disrupted" something else not so long ago, sometimes in living memory. If we protect truckers from autonomous vehicles, for example, we will have to explain to the laid off railroad guys why we did not protect them from the truckers. Why we did not protect the longshoremen from the shipping container and crane.
It's the government's responsibility to take care of its citizens, absolutely.
Making people do work that they know is inferior to what could be done by machines (or foreigners) just seems like an extremely degrading way to go about that. I'd much rather see a good chunk of the output of "license to print money" operations taxed and redistributed.