Actually that's not entirely correct. Yes, you can import pretty much any car to the US provided they pass the emission standard for the state that they are being imported into. For example, Alaska, Arkansas, Florida, Minnesota etc do not have any requirement for VIN, emission or safety so you can pretty much import any car there from anywhere. In California, where I live there are very strict emission standards; and they tend to get stricter over the years. That's one of the reasons diesel cars were not imported here even though they're available elsewhere although we have been getting a lot of newer VW's and some other cars in that are diesel powered.
However we have a lot more electric cars than anywhere else