Unsorted waste cost is often regulated to be higher than what the immediate costs are. And landfills are banned in a lot of places so the unsorted waste has to be resorted and the uncrecycleable parts incinerated[1].
Some European countries have essentially banned landfills; waste must be either exported (expensive, increasingly difficult), recycled (expensive) or burned (expensive, controversial).
Landfill costs (understandably) vary between countries. Got a lot of empty space? Cheap. Crowded? Not cheap at all.
Even in crowded countries, landfill land area is still a tiny percentage.
Its more environmental laws and how strict regulations are about seepage.