(start rant)
The simple answer is "China consumed less, and invested more".
The US can tax fuel and SUV, and invest in green energy. The EU can tax London's banks and offshore, it can slash its agriculture subsidies, and invest in tech and innovation.
The Western world simply prefers bigger cars and exotic vacations.
(end rant. Goes online to order Sushi for lunch)
The real issue in America is voters appear to have temporarily lost interest in infrastructure spending in favor of other uses of public money.
One other development that is quite startling in historic terms is a lot of modern western democracies is their relation with energy. I wouldn't be surprised if Germany was one of the first industrial superpowers of all time to turn its nose up at using a cheap energy source to further its economic successes.
Wartime footing usually disables many of the checks and balances used by democracies in favor of "we have to go faster now".
Most dictatorships eventually fall behind because exploitation, the fight for power and the mistakes of an un-checked leader become a burden on the country.
Whats the longest running democracy? And now does it matchup against the longest dynasty?
People always make these claims but the data just doesn't back it up. How many republic is france on right? 5? How many years did they last on average?