I asked a question on Twitter which lead to a fruitful discussion:
What's the difference between corporations doing business overseas to reduce taxes and New Yorkers who drive to NJ to avoid paying taxes on clothing?
The conclusion we reached was that it's about the corporations not doing business where they say they're doing business. It's the equivalent to an American citizen claiming income tax-free Las Vegas as their state of residency while living (domiciled full time) in California.
Of course, it's hard to blame a company or person for paying as little taxes as legally possible, but...