What a load of racist nonsense!
Ability to travel isn't limited by nationality. Wealth and desire to travel have far more to do with it.
Most Americans haven't the slightest interest in overseas travel. Maybe a hop over the border to Canada or Mexico, but that's a big step, and do they have the spare money?
New Zealanders, on the other hand, are the great travellers of the world, far more than Australians. Not that they have a lot of money, but it is expected that the have an "OE" = overseas experience. Because everybody else they know has.
But the real international travelers are Europeans. For those in Western Europe, crossing borders is just a matter of getting in the car, no passport required. or the train, or on the bicycle. How much money do you need to walk across the nearby border on a weekend? Some places, you can whip through several nations in a morning without stopping.
Think of the world as buckets of people, all more or less uniform, is a mistake. There are rich and poor in every land, and the factors vary.