They probably know exactly what they’re doing. Singling out Japan makes for a “better” headline to a mostly North American audience.
It’s also a bit of a clever headline. Compare the original headline and this one: “All major automakers continue to produce sports cars”. Both headlines could technically be true.
But the original headline lets you get away with stirring up some emotion e.g. “Japan alone is keeping the sportscar industry afloat, European, American manufacturers don’t care, sportscars are dying”. Life, death: strong words! It’s misleading and shitty journalism.