But what stops them from a: switching HQ, or b: starting in another country? It's not like the US has serious currency export restrictions, right? And little stops a company overseas to do business in the US, right?
I think the answer to both of your questions is, technically nothing. Once you have built infrastructure and a base however those kinds of moves are very costly in time, effort and money.
And little stops a company overseas to do business in the US, right?
I think legally, no, but for better or worse, there are a ton of tools that are U.S. only - an example from today: Microsoft Hololens developer edition is available only to the US and Canada.
