Why naval counter-drone lasers were slow to field

Were the United States and Royal navies making progress on laser air defence for killing drones?

Yes. The United States had already tested a laser at sea and Britain was planning for later ships, but neither service had funded broad installation.

An unfunded capability is different from technological vaporware. The United States had operated a ship fitted with a laser and continued development work. Britain also discussed directed-energy weapons for a later generation of ships. The slower transition to fleet service reflected the difficulty of persuading defence ministries and the Treasury to pay for the systems before the drone threat made the requirement urgent.