The point is that a focused laser will put a hole through the drone, much like an armor piercing round, but that is often insufficient to disable the drone. A larger ballistic projectile (think a solid shell or a rock) is much more effective. Alternative energy weapons based on microwaves and SPL also work well.
Already tested. Success rate is too low. A great deal of aenergy gets wasted.
Remember, this is about asymmetric warfare. If the number of rounds or amount of energy required costs more than the drone it shoots down, then it's not an effective deterrent. Militaries are looking for single-shot weapons to take down drones. Fire once and move on. It's the only way to deal with a swarm. Think about it for a bit and it will become very obvious.
