ahhhh.... I didn't see this earlier. No wonder u're mistaken.
JDM does not mean available in Japan. JDM, which as u know, stands
for Japan Domestic Model, are Japanese car models which are
officially meant for the Japanese car market. Outside of Jap car
manufacturers, I certainly don't know of any European or
Continental Car manufacturer who have JDM versions of their
cars.
So while cars available in Japan don't automatically mean they're
Jap cars, JDM cars are most certainly Japanese cars.