Those smaller / cheaper EVs might not be street legal in the US due to safety regulations: they need to allow occupants to survive a crash vs the massive monster trucks on American roads.
Getting Renault e-Twingo / Citroen e-C3 street legal in the US wouldn't really rise the production cost much. But nobody is going through all the trouble, because (obviously) almost no American would buy such a car, even though they start at <$20k new.