I think it's slightly biased because the US has an extremely strong CS founding, it's world leading without a doubt. This is pushed by a large number of excellent departments and groups like Microsoft Research and IBM (hell, even Disney) which churn out top tier research.
You cannot judge people on long lists of conferences. The people you cited have enviable CVs but only three or four peer reviwed journal papers (prior to 2010) between them. This is comparable to anyone in the EU. What are the impact factors of those journals? I have no idea and am unqualified to judge. It depends entirely on your field and what the big places to publish are. For me, an imaging PhD student, it usually starts with ICCV and CVPR (and of course SIGGRAPH), however the actual citations come from journals, not the conference papers.
I have been chastised by my supervisor for citing proceedings before - a lot of people don't consider them peer reviewed and that makes a big difference.
I know people who got papers in Nature or Science during their PhD posts. In astrophysics, people regularly get four-five peer-reviwed papers over the course of a PhD because it's a publication-heavy area. A single Nature or Phys Rev citation is worth a lot more than five conferences you attended. I probably won't publish more than a couple of papers in my field, but I'm not expected to as some of it is commercially sensitive (though I may get a patent out of it instead - and more importantly, a job!).
At the end of the day, does it matter? Very few PhD students are genuinely top tier. Most of us are happy making a dent in our little niche and will probably get comfortable jobs afterwards. Unfortunately things inevitably become a slanging match :(