Electrons (and all other particles with spin) have a spin outside of atoms.
This spin is taken into account at electron- positron colliders.
The spin is not relevant at high-energetic proton-(anti)proton collisions, as you don't care about elastic collisions there*. Deep inelastic collisions (the interesting stuff) are collisions between parts of the protons, where you cannot control the spin anyway.
*don't tell that the scientists of the TOTEM experiment. But the proton spin is so small that I don't think they care about it.