I might be totally wrong, but I suspect that it's linked to Napoleon spreading civil law over (continental) Europe. To my understanding (IANAL) the key innovation in the concept of civil law is something like Everything which isn't forbidden by the law is allowed which created a culture of precise and detailed laws While, still to my understanding US style common law let more room to the judge to interpret laws and make decision even if there isn't a law yet (which is why their judges are elected officials and that in the US abortion law comes from the Supreme court not from lawmakers)

The fact that we expect detailed and precised law is also why lawmaker will spend time to write them.

That said, I wouldn't mock too much the political mess in the US, most of Europe isn't doing that well. Belgium stays 1-2 years without government after every election, Spain has a region which unilaterally tried to secede, Hungary/Poland have serious authoritarians tendencies, the European council still decides who leads the commission rather than the European Parliament, and let's not speak about the Brexit fiasco, these are definitely symptoms that our system(s) don't work that well.