I have no idea if it works the "other way" for example a French plane taking off into IMC to travel back to France though...Maybe they don't visit the UK because the food is not as nice
I know for one I'd never dare to fly IFR in the USA without a clearance unless it was an emergency. This is the only trouble in the UK, the grey area between IFR and VFR. Without formality anyone can be IFR, nope VFR, nope IFR etc., which is not a good thing in my opinion. This probably also leads to people "pretending" to be VMC when in fact they are IMC - (not that it appears to have caused any accidents yet). Likewise this pseudo IFR does not help the pilot - I'd rather file a route, and have all airspace controllers on the route informed of it before I got there, so zone transits can be easily and quickly accomplished.
IMCr holders who use the rating must be pretty good though as it is the toughest sort of IFR flying in the world. You are resposible for flying and navigating in IMC, you are responsible for negotiating airspace transits and re-routing if nescessary, you are responsible for avioding all class A airspace, you are single pilot. By contrast flying airways is easy, join the airway, sit there, tune the radio, eat your sarnies.......
Regarding the stats, I can't remember where I saw them but yes, the UK is far worse than the USA re: fatality per 1000,000 flight hours but roughly half of where France is.........I'll see if I can find them.