Like who? How much revenue do they make, combined, compared to the combined revenue of US companies? Let's not kid ourselves here - I'm European, there are many things I like about the place I live, but the tech company scene is laughable here. It's hard to find anyone who is even capable of thinking beyond the 'I set up Active Directory network and fix pc's' or 'I make websites for the local pizza place' level.
(yes there are some counter examples, I know, but I'm talking about magnitudes, not frolicking in the margin)
Quite a few startups come from the UK, Ireland and Germany; in all three countries the alleged behavior by Square would be highly illegal.