RVR,
You have to be very careful comparing the number of PPL/IRs issued in the UK to the US. Remeber that the majority of UK-based pilots who want to fly in IMC will get an IMC Rating, not an IR.
I don't disagree with the point that you're making, just pointing out that if you really want to compare numbers, then you will need to add the IMC Ratings to the PPL/IRs before you can get anything meaningful from it.
FFF
-------------