It's worth bearing in mind in the UK there is very limited government support for pursuing a masters degree, whereas in France there is somewhat more (at the very least the Grandes Ecoles diplomas all are technically masters under the Bologna process I understand, and are usually government funded - in fact some classify you as a trainee civil servant and actually give you a regular stipend as well).
Also masters degrees in the UK are very expensive whereas in Europe in general they're fairly cheap - I don't know about France specifically but I know in e.g. Germany you just have to pay a nominal fee every term to continue matriculation and otherwise just have to pay your living costs out of pocket, so it's very cheap compared to the UK (and US, which is why a friend of mine from the US is doing his masters there).
Between those two factors, it's not really surprising masters degrees in the UK are relatively uncommon, since they're expensive and not well supported by government funding, so most just can't pursue a masters whether they want to or not.