Badly, generally. I'm struggling to think of a major country with more than two dominant parties that functions well. -XC
Well, most nations (as far as I'm aware) do tend to develop two major parties (NZ is an example - we have Labour and National as the two major players). The difference comes about when neither of those two parties is strong enough to rule without forming a coalition with another party or two. For example, in NZ, the Greens usually draw between 7% and 12%, so a Labour/Green coaltion is often feasible. Likewise, National will sometimes court smaller parties like NZ First or ACT for a coalition. The point is that minor parties share power, in proportion to their popular strength. That doesn't happen in the USA - and really can't happen, because of party entrenchment.
Well, it can happen from a legal/constitutional framework (see: Dixiecrat) but tends not to. Please note that I said, without prejudice, "major." I believe the scale/reach paradigm limits comparison between countries with 5M (or 20M) and countries with 300M in most particulars. -XC PS - We lived in Oz for a year and loved visiting NZ, a great part of the world. I would never disparage it.
First-past-the-post ensures being a third party rarely works in the States. When it does, they've ended up replacing one of the major parties; the Republicans replacing the Whigs, the Democrats replacing the Democratic-Republicans. That doesn't seem likely to happen in the foreseeable future, though I wouldn't be surprised if the Republicans end up looking an awful lot like the Libertarians eventually.
I've been told that the NZ system is largely based on the modern German government. There's 80 million-odd Germans, and they seem to be doing okay (I could be wrong about that though, I don't follow world politics very closely). People always mention the "scaling problem", but only ever as a way of dismissing the small country. No offense intended - or taken :-) And it's certainly true that the USA has not always been Dem. vs Rep. - but it has become entrenched, through legislation, over many years. I really don't know the best way to undo that (assuming you'd want to), since it's in neither party's interest of late.
Well, considering that Germany spends 1/2 of what the US does on defense and the rest of the EU 1/8th I'm not sure what "good" means in a geopolitical sense. Add to that the 1/16th spending on medical research, 1/8th spending on engineering, etc, etc and what you have is essentially an aging free rider system with a demographic time-bomb waiting to go off. No thanks, not here if we can avoid it. _XC
Examining another country's political systems is one thing. Adopting another country's policies is quite another.