Same in France: all the PhD students in computer science I know have finished in 3 years, or 3 years and 6 months (you can request a 6 month extension). You can't carry on after that duration because you have to be funded and be full-time (so no side job).
FWIW, these (IMHO absurdly) short PhD programs basically mean you need to do a postdoc for your CV to even be competitive with US CS PhDs -- assuming you want to do research in a top institution or research lab. So it's far from an obvious optimization.
That was not my experience. I did a PhD in quantum physics in the UK (Imperial College) in 3 years + 6 month extension. I collaborated with Oxford University and I was able to publish in Nature Physics, PRL, etc ... (in other words, the top journals in the field). I was offered post-doc positions but eventually went to industry.
I really enjoyed my PhD as a time to learn and think about deep and difficult questions. Regarding employment, I think it shows that you can commit to a problem. It shows perseverance and drive. And those are good skill to have at any technical job.
The view from Europe is that since students in US PhD programs spend their first two years doing courses they come out with similar actual research experience.
