Air forces using their own oxygen masks

[Alexrey]

I was just wondering why air forces use different oxygen masks to each other even though they may fly the same plane or be part of the same coalition. I thought technology such as this would be shared amongst partners. So far I've noticed that the USA, UK, Russia and Japan all use their own specialised oxygen masks (and there are probably more).

 

To me the UK seem to have the most uncomfortable looking mask as it always looks like its about to fall off, but I guess it must be pretty decent to be used with the Typhoon.

[nscode]

If you can make something yourself, there is no reason to import it.