Having lived and worked in the US for a decade, as a German, and having had time to think about many things:
I think a key difference between how the US works and how Europe works lies in the private sector and the people. When you build a new company in the US, you have a lot of private infrastructure and people to be active in all of the states. In Europe, this does not exist in that form. Here, all the investors are focused on their own country. Sure we have plenty of firms active in many EU countries, but the level of support especially for new firms is orders of magnitude lower than in the US. From languages to social issues to attitude and expectations of common people, the EU is much more compartmentalized and it is significantly harder to have EU scale.
So there are two issues, and the side of the government is only one. The private sector and the investors have to do their job too and provide their own side of the EU wide infrastructure.
We also don't have EU-wide media that needs to support the development of a shared EU identity, and many other things that unite the US population as one people. Much of that has to come from the private sector, from the rich, from investors. But apparently they don't think big enough here in the EU?
Perhaps, but I wonder how much having so many different languages contributes to that. In the US, most people all speak English (though there's a growing Spanish-speaking population, but even here most younger ones probably end up being bilingual), so there's not that much to do for your company to do business in all 50 states, depending on just how much interaction with state governments you require. And state laws are all pretty similar usually. Not so in the EU.
Lack of a common language must be a factor in scaling - the amount of effort printing required information in different languages is already an overhead (e..g instructions on medications).
Also in the US, somebody in California can give telephone support to somebody in Rhode Island; not so easy to get somebody in Sweden to give telephone support to somebody in Italy though.
I think a key difference between how the US works and how Europe works lies in the private sector and the people. When you build a new company in the US, you have a lot of private infrastructure and people to be active in all of the states. In Europe, this does not exist in that form. Here, all the investors are focused on their own country. Sure we have plenty of firms active in many EU countries, but the level of support especially for new firms is orders of magnitude lower than in the US. From languages to social issues to attitude and expectations of common people, the EU is much more compartmentalized and it is significantly harder to have EU scale.
So there are two issues, and the side of the government is only one. The private sector and the investors have to do their job too and provide their own side of the EU wide infrastructure.
We also don't have EU-wide media that needs to support the development of a shared EU identity, and many other things that unite the US population as one people. Much of that has to come from the private sector, from the rich, from investors. But apparently they don't think big enough here in the EU?