Mmm, there were electric car companies in the US before Tesla, started within a decade of Tesla.

AC Propulsion (1997) tried producing the t0. https://en.wikipedia.org/wiki/AC_Propulsion_tzero

In January 1996, Corbin Motors began work on developing an electric vehicle. The Sparrow passed final testing for Department of Transportation certification in April 1999. In September of that year, the Sparrow production line began manufacturing multiple vehicles in Hollister, California. - https://en.wikipedia.org/wiki/Myers_Motors

They weren't successful, but that's different than your point about "nobody has started a new car company in the USA in many decades".