The EU is not very comparable to the US. Pass all the laws you want allowing mobility and trade between EU members, you’re still not going to bridge the deep language and culture divides between the countries.
The US is a true single market because English is the dominant language and because everyone from the Deep South to Alaska consumes the cultural products of Hollywood and New York and the technology of Silicon Valley.
Right, if you look at banking (which is regulated nationally) there is very little competition between banks in EU states. There are examples in other industries.
But I didn't compare it with the US at all, all I said was: the EU was formed, in part, because people in the 60s believed that US growth was stronger because the domestic market was larger (and that scale advantages were critically important to business success). This was a very common view in the 60s in the UK too (and held by the govt which embarked on a huge investment/forced merger program to boost domestic production that ended in disaster). And it was totally wrong, as subsequent economic performance demonstrated (the reason why the EU's single market is incomplete is nothing to do with language and everything to do with politics).
And how do you explain those products being dominant in the rest of the world? The UK went through this, tried to create globally competitive firms with scale by forcing companies to merge, almost all of them went bankrupt (have you heard of British Leyland? No?) because they were mismanaged, and produced bad products no-one wanted. It was like trying to add one to one and make twenty.
The US is a true single market because English is the dominant language and because everyone from the Deep South to Alaska consumes the cultural products of Hollywood and New York and the technology of Silicon Valley.