It's just one part of amateur radio, but Europe's HAMNET (mentioned in the article https://www.tapr.org/pdf/DCC2014-TheEuropeanHAMNET-DG8NGN.pd... ) is a lot more developed than what we have in the US.

I think Field Day is more of a US thing. It is really setup around an official contest put on by the ARRL, which gives extra points for operating off-grid, or portable. There are no extra points for international (DX) contacts during Field Day operation though, as opposed to some other contests.

But for Amateur Radio in general, it is a very international organization, with widely different areas of interest.

Radiosport and High Speed Telegraphy competitions are very big in Europe, and the demographic in EU is a bit younger than in the US:

Some links:

http://www.rufzxp.net/toplist.htm

and

http://www.wwyc.net/?p=members