Well maybe. But I guess that they couldn't find any other way to prevent Apple Pay. After all, neither CVS not Rite-Aid did anything to enable it - it "just worked". So even though PayPass/payWave had been grandfathered (it seems), they felt that they couldn't continue to have Apple Pay work. Or something like that. Whatever it was, it was dumb. Still is.
Look at it another way. When you bring the money back to the U.S. you get your original payment back (not in reality, but as a credit) and then pay just the U.S. tax. So you're not paying full-rate tax twice, which is most people understand by the term "double taxation". Note that this DOES occur in some situations but not in this one. Here you pay no more, but no less, than if the money had come directly.
Sort of. It was "subject to tax" but in a place where the tax rate was zero. So there has not been a tax payment on it, but it has been "taxed" because it was subject to tax. A subtle point but one much loved by corporate tax advisers.