I'll drastically oversimplify here, but in a collider, the particles being collided are highly regimented. First, you have a very specific type of particle you

I'll drastically oversimplify here, but in a collider, the particles being collided are highly regimented. First, you have a very specific type of particle you want to move around, like a proton (and you had best hope you picked a charged particle so you and move it easily with an EM field). Second, you have a very specific direction for that particle so you can smash it against something else. Third, the energy the particle is at at the time of smashing is well-known and very high. It's all very specific. Annihilation is too uncontrolled to help, often in terms of direction. Accelerators are all about trying to add just a tiny bit more velocity to something already moving at 99.99% of the speed of light, in the exact direction that particle is already going in. So it is both precision and vanishing results. It's a tricky situation.