EU has done really well on passing big laws such as GDPR in the recent years, while the US can’t even seem to decide whether to fund their own government. Why do you think Europe is doing better than the US? One would think that since EU is more diverse it would be harder to find common ground. And there were examples of that during the Greece debt crisis. But not anymore, it seems.
With an actual, working multi party system there is less polarisation, and most parties don’t actively hate each other to the point of opposing anything the other supports.
Also the political system behind the passing of law is different, although I don’t know enough to explain it.
I would agree. To the extend that OP’s thesis is true (which I don’t think is fully true, but also not fully wrong either), I also find that the readiness to compromise both at the EU level and in most member-state parliaments that eventually need to transpose the directives into national laws, is a difference that stands out.
A multi-party system helps too, because there can be situational alliances that do not divide the parties internally. E.g. in one topic the Social Democrats, the Moderate Right and the Liberals can be on the same side and pass something (probably a free-trade deal) and on another topic the Social Democrats, the Greens, and the Left can pass something else (probably an environmental regulation). When there are only two parties in the legislature, such alliances break party lines, so it’s a higher hurdle to overcome.