Because Islam is one of the things that "the West" is defined in opposition to at the moment. It's part of "Them" not "Us". Judaism is currently in the "Us" club (at least in polite society), after a couple of millenia very definitely not in it.

In fact, the further I get from my childhood Chrisitan indocrination, the less difference I can see among the various branches of the Abrahmaic religion.

In fact, I've just realised that if you want to run around splitting the world up into cultural groups then Europe and the Mediterranean basin and stretching through the Arab world is a natural grouping: shared religion, significant ancient trading and political links,  shared philosophical and political heritage to a large extent until very recently. Then you'd end up with Asia as the other significant cultural group with India as a bridge between the two.

I suppose you'd then need American and Australian groupings, both of them significantly less linked to the rest of the world than the mainstream  Asian and  Western groups.