That’s only because of political entrenchment. If Europe loosened their labor laws and made other reforms to bring them in line with American business law, they would probably catch up to American GDP per capita pretty quickly. As it stands, US GDP per capita is 40% higher then even Germany. Do you think the Germans aren’t capable of producing at the same level as the US?
It does not seem like you want to give any contrasting explanation so much as a thought.
Your 40% gap turns into an 18% gap. Further more libertarian economies don't look particularly exceptional.
Together this suggest that the differences in GDP are much more easily explained by existing wealth and foreign policy/trade, instead of domestic factors.
Small base growth is easier (that’s the example you give), but catch-up growth in large economies is damn near impossible.