Edit: Basically any car from Suzuki would be a hit in the US: https://www.suzukiauto.co.za/new-cars
They are perfectly legal to sell. There's just little demand and most manufacturers have discontinued sales.
I own a not-quite-that small car and the manufacturer discontinued US sales for the same reason - the lack thereof. That's why the Smart Fortwo discontinued sales in the US in 2019. The US market for good or for bad just does not want small cars. Many manufacturers are even dropping their sedans for sales reasons; e.g., Ford dropped the Fusion and Focus.
I didn't much care either way, but I do still consider this when comparing new vehicles.
This is blatantly false. See: the Mitsubishi Mirage as just one example.
(I don't know about erikw's claims about small cars being illegal in the US. So I don't want to express an opinion on that.)