One doesn't need to embrace Beardian conspiracy theories to believe that the Constitution was designed to limit the central government's ability to extract resources from wealthy citizens. As a result, it has succeeded in checking the rise of an American socialist state while all the larger countries in continental Europe have socialism-friendly political institutions.
It wasn't always so. At the start of the 20th century, the U.S. looked progressive compared with Europe's empires. The big difference between the U.S. and Europe is that the U.S. kept its 18th century Constitution, while most European countries discarded theirs. In a wave of revolutions and quasi-revolutionary general strikes, European countries, one by one, replaced their older conservative constitutions with ones often designed by socialist or labor leaders.
Some small nations introduced proportional representation before World War I in response to uprisings that threatened their governments' stability, but the war was a watershed for great powers like Germany, Russia and Austro-Hungary. These nations' armies had traditionally checked militant labor unrest, just as in the United States, but during World War I, mass mobilizations and steady demoralization broke the armies' will to fire on rioters. As the armies' policing power vanished, empires were upended by left-wing revolutions. The new constitutions of these countries were written by socialist leaders like Friedrich Ebert, who were determined to craft institutions, like proportional representation, that would entrench socialist power. France had a constitution drafted by a socialist-heavy group, but this had to wait until after its defeat in World War II.
By contrast, the U.S. has not lost a war on its home soil and thus has never faced the internal disruptions caused by such a collapse. The U.S. military and private armies, like Pinkerton's, have always been able to subdue agitators, such as the Homestead, Pa., strikers who faced off against Andrew Carnegie in 1892 and the jobless World War I veterans who marched to Washington in 1932 to ask for their bonus, and were dispersed -- with swords drawn -- by Army troops.
