I think the motive for charging more is simply collecting more, and money from foreign tourists is low-hanging fruit. Westerners tend to want to know where the money is going—to more tea money, to needed projects, or to invest in projects to increase attendance, for example. When a museum in America wants to add more space to display new art, it advertises the project, gets media attention, and generally builds a Buy-In for people to donate. People with extra money who can afford to donate to a project can also be recognized. Projects do not have to be big; improving or building new trails, building new restrooms, and renovation projects, for example.