“”Can we forgo the copper cables now then?””
No. The testing was done in an uninhabited area. There’s a good reason why there were no humans “in the way” of that focused beam of light (tests at the U.S. Army’s White Sands Missile Range). What happens to humans if that beam hits them? I’m betting that DARPA isn’t at all concerned with the answer to that question. $$$ is the goal here. It is “Big Govt”, after all.
“This scientific experiment turns electricity into a tightly focused beam of light, sends that beam across open air, and then turns the light back into electricity at the far end.”
Darpa has laser weapon projects.