Unions are really powerful in corrupt and underdeveloped countries. Correlation is not causation, but still, it's frustrating for workers in those regions.
Danmark and Finland topping the list have 70% membership.
Unemployment insurance plans seem underrated in general by FTEs, both in the US and elsewhere. Without it, your ability to exercise both halves of "voice or exit" in the corporate world are severely curtailed. Like life insurance, it's relatively hard to game as a policy - it's usually pretty clear when you lose your salaried job, just like it's usually pretty clear when you die. I see few downsides, especially if you live cheap enough to pay all of your bills on that X% of your income anyway.