Earlier quoted context omitted.
There is no country called EU and there is no single market in that a startup could scale seamlessly in all 27 members - it'll still have to follow local laws. So it's mostly a matter of scale - if you can't outscale US/China/India, you can't compete with those that can.
That is somewhat of an indictment of the "single market" idea, or, more precisely, of its implementation. We still have shocking differences not just in tech, but in food quality across the EU. Whatever sells in Czechia, Croatia or Bulgaria tends to be a) more expensive than in Germany and b) less good. I can't imagine the same happening in the US; Mississippians wouldn't tolerate being fed with worse cheese than New…
And yet, it's the case ? Sure, you can find the same products if you go looking, but the average food quality between those two states will be wildly different. And that's without taking into account that the average food quality in the US is awful.