It's very simple to found a company in the US that has access to the entire 50 states and all of the investors therein, with a single/simple accounting to manage. And you don't have to live in the US to do it.

Europe/EU/EEA don't have a comparable setup. Found in one country, deal with workers in many, filings in all of the countries you're doing business, and more.

The new proposed EU Incorporation would go a long way to lowering the bar for getting started and accessing pools of funds between investors in different countries.