This isn't yet decided. Microsoft and the DoJ are still arguing about this in the court system, which so far has ruled that the US government cannot compel Microsoft to release data it holds in Ireland. It's currently waiting for the DoJ to decide whether to take it to the Supreme Court: http://www.politico.com/blogs/under-the-radar/2017/01/micros...

That sounds very dangerous. What would happen if Amazon simply had a 99% share, but 1% was held by another purely Irish company. Amazon might elect the board and the subsidiary might 'lease' intellectual property and capital from the parent company, but I don't see how you could argue it is subject to US law in any way.