My best guess would be based on demand, efficiency and money. Airlines in the U.S are a lot larger then those in Asia when it comes to fleet size. It no longer makes sense to hurl one of an airlines fifteen 777s on an ATL-MCO-ATL once a day when it can be done 10 times a day on one of an airlines sixty five 737s. U.S airlines make more money using wide bodies on international routes. They would need to charge international fares on short domestic flights to pay for the operating cost of a wide body, and we know how hungry the flying public is for cheap fares.