Apparently L4 and L5 type Lagrange points, the kind that occur 60 degrees before and after an orbiting planet on the orbital path, act like virtual masses. They can capture junk and hold it without any extra lucky inertia-robbing collisions.
Yes, they do, L4 and L5. Objects in there have elongated, kidney-bean shaped orbits. But an object passing into the region would just shoot right on out the other side if it doesn't hit something hit or if its speed is too high for solar wind to make a difference. Once it is in orbit, it will stay, generally, although objects can escape on their own, too.