Interesting. I wonder if it takes an immigration lawyer and a lot of $ to do it, or whether it's something mere mortals could do. Mappers from Europe certainly seem to fit the bill as extraordinary!
It's certainly an art form and perhaps mapping for high profile events in Europe would be the equivalent of accolades for acting.
The O visa is something I researched extensively, in consultation with an immigration lawyer. An interesting mechanism. This stuff isn't that hard but somehow it seems like surmounting Everest to orienteers.
There are other ways to get non-extraordinary people in the US, too. My landscaper brings seasonal laborers from Mexico every year, with appropriate visas. I imagine H-2As.
And then there is an H-1B. Another wonderful option if a little bit of planning was undertaken.