What really happened (in my opinion) is that 25 years ago, the EU failed to recognize how transformative the internet was about to become. As a result, many US tech giants gained a first mover advantage and became entrenched in the EU.....services provided by today by Microsoft, Facebook, Google, Amazon, Netflix, Facebook, Square, Paypal, Dell, etc, suck hundreds of billions of dollars out of the EU every year and into the US.
I don't cast any moral judgement on these companies, just calling it how I see it. One piece of good news for the EU is that it seems they have learned from their mistake 25 years ago, and as a result are trying to become leaders in emerging technologies....I know for a fact that EU companies/agencies are doing very well in their development of manufacturing robotics, autonomous shipping, renewable energy, autonomous driving, etc....10 years from now, autonomous European-branded cars will be powered by European software, not American software, like we see powering so much of the EU today.
Also, another factor has been the challenges faced integrating EU countries into a singular system (example, EU countries are not allowed to run budget deficits in excess of 2% annually, while the US routinely runs 6% annual deficits). This has caused countries like Italy and Greece to be a real weight around the neck of places like Germany and France.
Anyway, there is a lot more that I could go into here, but I don't think it boils down to simply "hur-hur, US stock markets are higher because America is so much better than the EU."
Just my two cents.