The US can work as a federation because the original 13 colonies were culturally homogeneous, English speaking, predominantly protestant. Nominally different, they shared many more similarities than EU countries have: from FPTP to the prevalence of common law, things that even today they share with the UK.

In the US, several migration waves from different countries, cultures and languages had to assimilate, they simply had to learn English to find a job, deal with taxes, government, education, healthcare…

Compare the EU to that: Europe is not a continent where a small polity simply expanded, Europe is a continent with several established polities, each with a unique culture, language and history, quite often in competition against each other, but always, way more different than the American states. European countries are fundamentally different, something that doesn't apply to the US states.

A language embodies a culture and a certain way of seeing the world. In the US we have English. In the EU, there are 24 official languages. Why do you hope 27 countries speaking 24 languages can somehow create a common culture, ignoring several centuries, even millennia of divergent history? What percentage of Italians or Romanians can speak fluent English or, say, German, the most spoken language in the EU?

Every American knows what CNN, WSJ and USA Today are. How many Poles know what the BBC is?

What kind of allegiance do you expect a normal citizen from any EU country to have to this federation? Why do you believe his allegiance to this federation to be more important than his allegiance to his home country?

There are 27 armies and the same number of military procurement systems in the EU. If a European federation is possible as you claim, why aren’t you taking steps to have just one?

I don’t see how a smart person can genuinely believe you can create a European federation with so many differences, languages, cultures, histories and competing interests.

Maybe you can prove me wrong?