The particular issue described above (raising "base" prices to show a larger discount) is common in USA but illegal and thus very rare pretty much everywhere else. I'm quite sure that amazon.de and amazon.co.uk didn't apply this practice.

There's a rather common set of "truth in advertising" laws (e.g. to show a "x % off", the base price can't be made up ("recommended price") but you must have sold this item for certain amount of time for that old price already, the sale can't last for more than x months (in that case, that becomes the base price), etc, etc. USA has chosen not to adopt such laws.