Well, the population of each of those cities is huge. There are more people within Shanghai City than in the state of Florida. Add the number of people within a few hours' drive or train ride and it's almost as high as the US population. Japan has a population about 40% of the entire US - and in a much smaller area. Also I think it's kind of hilarious to consider the three Asian parks "close together." Hong Kong to Tokyo is a 4-hour flight, which is comparable to Orlando to Anaheim.