"a rather modern invention" Congestion charge is a rather modern invention as well, because the amount of cars in some city centers exceeded the tolerance of t

"a rather modern invention" Congestion charge is a rather modern invention as well, because the amount of cars in some city centers exceeded the tolerance of the locals and the capacity of the roads. Borders can be soft/open as long as a modest amount of people crosses them. In a world of 8 billion people and relatively cheap travel, open borders would result in massive flows of people into several desirable locations - whose citizens aren't happy about such prospects.