Just for the record, I'm no fan of U2's music and some of the things he does I personally admire while others I don't. Also, just so you don't think otherwise, we file both Israeli and US tax returns every year and pay a fortune. Our biggest "loophole" are deductable charity receipts and both country's tax authorities deem our total of donations as exceeding the maximum deductable allowed.
If no laws were broken, I don't see anything morally wrong with this. Each country makes its laws. Some are more advantageous than others. It's a fact of life.
Ireland intentionally competed for people's business in the first place. Now Holland is competeing harder. It's a free market.
Paying taxes in principal on a volunteer basis when the law doesn't require you to? Does anyone here do that? I don't think so.
