It depends on what "allowed" means. The penalty for doing so exceeds that for many minor crimes: http://en.wikipedia.org/wiki/Expatriation_tax#United_States

Was expatriation a serious problem for the US? It seems a bit of a severe step to take for someone who is already wealthy.

Not to mention it raises the question - if someone renounces their citizenship, what right does the country have to tax them? Doesn't tax come with the right of representation?

I guess you cannot avoid a few misses in that much information. I found most of it to be true.

That said, I think it glosses over the fact that US states have huge differences and he has only experienced a subset of them.

Author probably never went to Poland - there is much more drunk people in than in Germany. And I never experienced problems with Germans in Germany. And untaxed work in Germany was quite prevalent prior to last year May. And some other things that should be corrected.

I think he meant that if you want to avoid paying U.S. taxes, you have to give up citizenship, which is true to my understanding.

No, you have to pay taxes for 7 years post loss of citizenship.