Earlier quoted context omitted.
Slow and easy to kill? Seen a drone race? At what range and with what weapon would they be easy to kill? How long would the kill take? At what range could the drone be killed at? Sure often drones fly in straight lines or hover. But in an adversarial environment they could easily move pseudo randomly and be quite difficult to kill.
Current point defense systems are already capable of placing a 20mm round with a muzzle velocity of 1000m/s onto a falling mortar shell in the last three seconds of its flight time. How hard do you think drones are by comparison?
Which are available to how many militaries?