Legalities don't drive profits. If anything the US was simply lucky in thr 50s to not be war torn and rebuilding it's cities post war.
The only thing special is our geography and history. It's really hard to launch an attack unless you're in Canada and Mexico. So the US smartly made treaties and agreeemtns instead of repeating the bloody history Asia and the now EU went through as they constantly battled neighbors.
Only Australia has such a similar advantage and instead they had to war with nature's deadliest critters trying to kill them (they arguably lost).
I'm a bit stumped that you don't consider treaties and agreements to be legalities.
I mean sure, in the 50s the main driver of prosperity was whether a country had avoided being invaded and that isn't necessarily a result of a country's legal system. But the 50s was a very long time ago now and the era since then has been quite equal-opportunity outside pockets of disaster in Africa and the Middle East. The USSR, Chinese, Euro and US experiences haven't been determined by external factors or historical determinism as much as internal policy choices made in the 60s, 70s, 80s, 90s and 00s with a 20-30 year lag before the decisions start to turn up in real life.
Even if we indulge in wild conspiracy and pretend there is a shadowy cabal in Washington that decided to crush the USSR and exalt China economically, that cabal would have had to implement its decisions by somehow guiding internal policy choices in the respective nations. Nobody has managed to do anything to either of them through external pressure that holds a candle to the internal choices made.
The only thing special is our geography and history. It's really hard to launch an attack unless you're in Canada and Mexico. So the US smartly made treaties and agreeemtns instead of repeating the bloody history Asia and the now EU went through as they constantly battled neighbors.
Only Australia has such a similar advantage and instead they had to war with nature's deadliest critters trying to kill them (they arguably lost).