How does the government get to decide that a big car that looks like a truck is OK but a big car that looks like a car is not?

Lawmaking, when done well, is the art of spotting unintended consequences. Many parliamentary democracies in fact have a department for that, sometimes called the privy council office, made up of bright long term civil servants (not politicians) who advise each new batch of elected riffraff on new legislation before it is introduced.

But back to cars or the lack thereof---

The US drives pickup trucks because there is an IMMENSE tariff on imported ones, so they are disproportionately profitable. (the temporary "chicken tax", don't ask)

And if I understand correctly, the reason SUVs became popular is because they don't count as "cars" for fuel economy rules, so the auto companies spent billions convincing the public that driving a truck was a reasonable and desirable thing to do, as that was cheaper than trying to find a way to make fuel efficient cars desirable. For example in Canada without that perverse incentive, in the relatively early years of this nonsense, minivans (higher efficiency with the same internal space) outsold SUV's 2 to 1, but the reverse in the US.

Sometimes lobbying is more cost effective, sometimes brainwashing the public is more cost effective.

Did I miss something, or is it true that no US car maker still makes what one would consider "cars" for the US market? A couple of niche things like the Mustang and Caddy, but not much else?

Ah, imagine the joy of driving a Ford Prefect 107E that actually worked...electric windshield wipers, for example, and a nice fuel injection unit.

Jim