Plagiarism Haunts Europe
bbc.co.uk
bbc.co.uk
Long answer: First you have to distinguish between the different European higher education systems which are merging only slowly and thus can't be considered uniform. Everything I write is based on the situation in Germany, which may or may not be similar to other northern European countries.
The _average_ PhD given out in Germany can't compete with a PhD degree from Stanford. However, the _average_ PhD given out in Germany leaves the _average_ PhD given out in the US in the dust. The reasons are as follows: In Germany, you can't just open a bunch of universities, accredit each other and start giving out degrees. Every University has to be accredited by the state and most universities (including all of the top tier universities) are run by the state. In addition to that, it is illegal to call yourself a PhD in Germany if you are not really a PhD (ATTENTION REST OF THE WORLDERS: If you come to Germany be sure that your degree is recognized or you might run into this.). Degrees are taken very seriously throughout German society, so "the people" demand quality control.
Also, at least in the hard sciences, plagiarism will make you a pariah. Once you are found out to have plagiarized something, people won't want to touch you with a ten foot (approx 3m) stick. Every physicist knows the name Jan Hendrick Schön.
What you actually see when you look at the case of Guttenberg and others is a bunch of people (quite possible mainly hard science folk) banding togehter in a wiki and dissecting some controversial cases from the soft sciences. The big plagiarism cases in Germany of the last years took place primarily in the realm of 300-page text only PhD theses in social fields or law.
Looking at it from the other side, you should consider wether or not plagiarisms are easier to be found out in Europe or the US. I really appreciate the no-nonsense attitude that Americans generally have and I don't doubt that a media shitstorm would ensue, should a big name politician be caught at something like this in the US, but the American system has a bunch of things against it. To list a few: Everybody needs a degree, no one has the time/interest to check PhD theses after the fact (would you start a guttenplag wiki?), more money is involved, translation plagiarism is very unlikely to be found out.
Which means that while you can start a bunch of fake universities and have them start an accrediting agency, it isn't the case that that agency is considered equivalent to, say, the Western Association of Schools and Colleges (which accredits Stanford, among many).
You wrote: "In addition to that, it is illegal to call yourself a PhD in Germany if you are not really a PhD." My understanding is that the rule is a bit broader than that. For example, http://chronicle.com/article/What-s-Up-Doc-German-Law/40636 highlights an example where the "director of a prestigious research institute in Jena, Germany", with a PhD from Cornell, was charged with Missbrauchs von Titeln because the law did not then allow him, in Germany, to call himself a "Doctor" - Cornell being outside of the EU. The "state education ministers met last week and decided to allow holders of degrees from designated American universities to call themselves "Doctor."", so this is probably not a problem now.
However, it does seems to mean that Germany has to 'accredit' that a given US PhD program is good enough for a recipient to deserve the title "Doctor" in Germany.