It didn’t take Europe near that long to rebuild. In fact the early 50s showed some of the greatest growth in Western European history. By the mid 50s agricultural production surpassed pre war levels for example.No mostly because for the first 20 or 30 years we where busy building ourselves up into a superpower while the rest of the world was trying to re-build.
You can't ignore that we where the only industrialized country that was pretty much untouched at home by the war. Our cities where not battlefields, our factories where not bombed.
Europe was pretty much flattened by warfare. China had that war and their civil war plus a crappy commie government.
Also the EU isn't a single country. They only recently within the last 15 or so years gotten one single currency. They still all have kept their native languages. So I don't think you can quite treat them like they are the United States of Europe. At least not yet.
I am guessing that if you look from the 1980's onward we don't have such a big advantage.
My suspicion is that the gap increased in the 80s and 90s but I’m not certain.