Most of the democracies of which you're referencing use proportional voting systems often paired with a parliamentary system. That system in particular makes it

Most of the democracies of which you're referencing use proportional voting systems often paired with a parliamentary system. That system in particular makes it phenomenally easy to replace politicians and tends to work most effectively as a coercive device against bad behavior. The reason for this is that it minimizes the necessity of strategic voting. In the US it doesn't matter if the #1 candidate only got 10% of the vote. As long as the #2 candidate got less than 10%, then #1 gets 100% of the seats and political power. Because of this, voters have to factor in the insidious 'electability' into their decisions. Fewer people than ever identify as republican or democrat, yet they retain very near 100% of seats at all levels. This is what I was alluding to when mentioning that part of the problem is our system. Compare this to a proportional system where if there are 10 seats available then gaining at least 10% of the vote, in general, tends to guarantee you representation. This makes strategic voting much less of a concern. Even the 'Pirate Party' has managed to win representation in a variety of nations similar to those you allude to. And for the sake of brevity, I'll omit more precise discussion of population size and diversity here. But those factors need also be considered. Compared to the nations you're mentioning, the US is huge and incredibly diverse. Democracy is redundant in populations where views tend to remain fairly similar throughout as any action would tend to be the will of all. On the other end, in a nation where everybody held views often mutually exclusive, democracy would be dysfunctional at best as any action would please one group to the offense of all the rest. Of course every nation's reality lay somewhere between the opposite extremes, but where the nations you describe may lay closer to one end, I suspect the US lays closer to the other.