Why is Hokkaido farming different?

I always assumed (mainly from Murakami’s A Wild Sheep Chase) that it was mainly a geographical thing, until I came across this:

“As Hokkaido was colonised by Japan in the 19th century, its agriculture was much influenced by American farming methods introduced by the Japanese government from the start of the modern period. Its landscape is dotted with American-style silos, grain elevators, and farm buildings in primary colours that one does not see in Japan  to the south”

The Cambridge Companion to Modern Japanese Culture page 23

How did sushi become popular outside Japan?

“There is no doubt that the positive images of Japan’s cars and electronic appliances as high-quality and advanced have been helpful in spreading similar images about Japanese cultural commodities. If sushi were a delicacy of a country without industial might or sashimi a health food of a remote village in a technologically disadvantaged region, it is doubtful if the cultural diffusion of these foodstuffs around the world would have been possible”

This (from the otherwise very interesting Cambridge Companion to Modern Japanese Culture), sounds like complete crap to me. How do you  explain the spread of Thai food, then, just to give one example? And why sushi and sashimi rather than takoyaki and soba? Unfortunately, though, I don’t have a better answer to the question. The first thing that sprung to mind is the lucky chance of first becoming famous in the always influential area of California, but Korean food certainly hasn’t spread from there in the same way…