In what respect is US one single large country? Texas and California feels as different as Shandong and Shanghai. And not sure if a flame war will happen if I try to compare Hawaii and Taiwan :p
compare that to spain and hungary, for the europe example. or tamil nadu and punjab in india. the right comparison for china isnt shandong and shanghai, it's like shanghai and guizhou or something. i promise you the cultural, culinary, and linguistic differences between shanghai and guizhou are WAY bigger than between texas and california. thats the point being made