IFAIK about 3/4 of the Canadian population lives within 100 miles of the US/Can border. The notion that Canadians have lots of space is an illusion. I believe Canada has a lower percentage of rural inhabitants compared to the USA.
Canadians are more physically active than their American cousins which might account for higher per capita participation in sport and by participation I mean playing not watching from the armchair.
Personally I'm not a fan of big games, I'm probably not the only one. I don't think big game participation is a useful metric for gauging paintball participation, that would like using MMORPGs as an indicator for video game participation.