Easy access to funding, a funding culture, a bootstrap entrepreneurial culture, a big tech-savvy audience, a spirit of creativity and experimentalism, a socially and economically mobile milieu... there are so many things that we just don't have in Europe.
It's no accident that (what feels like) most German web startups are copycats of successful American products, sometimes down to the look and feel of the product. Building new stuff is actively discouraged here, nobody likes doing bold experiments: not customers, not investors, not even developers.
Looking at seed funding behavior is a very shallow thing to do in the face of these big hulking cultural differences. Playing around with money, having an exploratory approach to your career, risking failure - those things are just not done in Europe.