A combination of two things. Award charts tend to have less thought put into the prices than do fares (a long holdover that comes with the general model of area based awards instead of distance or revenue base - about the only reason I can come up with why the GF difference is much higher for Europe). Secondly, I think there are people who would say GF is comparable or only slightly better than J on some *A partners. One way or another, demand for GF is pretty low.