For the glider example, it likely has to do with the basic design philosophy of the builder, as well as nomenclature.
If a glider is actually a high-performance sailplane, focused on competitive long-distance soaring, then the wing will be designed as much for speed as for glide ratio (L/D). A "1 degree" flap setting or similar may be incorporated to get better L/D at lower speeds for thermalling. OTOH, other sailplane mfgrs will instead incorporate a "negative flap" setting for high-speed dashes, while the normal 0 deg setting is used for thermalling.