It's a scandal indeed.
Why do we have a tax system that an accountant can do some jiggery-pokery and suddenly not be liable for billions in tax?
Because stupid politicians don't know how to draw up a fair tax system, legislate it, or enforce it.
Amazon ARE NOT BREAKING THE LAW. They have clearly said that. If they were lying, you could take them to court. Hence, the problem lies not with Amazon (who are required to provide shareholder value), but with the tax system that allows such easy and massive circumvention in a legal manner.
If you want to point fingers, point them at your golf-buddies who have created a tax system full of loopholes that they themselves exploit.
If you want to fix the problem, tax it properly. Actually sit and ask an accountant "how would you avoid this", and then put in measures to stop that. Or, alternatively, make a tax that you can't avoid (e.g. one on income rather than profit).
I'm sick and tired of politicians blaming multi-national corporations who have no morals for failing to comply with something which is only a moral obligation for them (not legal). If you have a problem with that, solve it, by making it a legal obligation. Then you can take them to court.
It's like me blaming people for taking all my belongings when I knowingly offer them on the street corner "for whatever you want to pay me" and I end up losing everything in my house for £4.38. Perfectly legitimate, and who's the idiot? The guy who paid me a penny for my entertainment system, or the guy who said he could have it for that?