it's all a matter of production differences in certain countries and their standards.
goldfill is an American standard and was either not popular in Europe or was considered to expensive to produce.
this is probably the reason why you won't find GF cases on European top-shelf watches including the GP Casquette.
legal issues might have also been involved as it is almost impossible to quickly test a heavy GF case for solid-gold (without drilling to the base).
even for GP you have to scratch the case before applying the test acids.
only some German and French watches had rolled goldplate (RGP) cases in the art-deco period.
this was called Double and was limited to flat, square and easy to make cases.
RGP is also considered to be GF, especially that all bracelets were made with a RGP process but marked GF.
Omega case below, also marked inside the caseback.
