like I get DEW and lasers but the biggest factor is the energy. You need LOTS of it and concentrated. Unless there's some sort of reactor in there, I doubt they could light a fire from 10km up in the air.
Discussion
The whole point of a laser is that you don't need a lot of energy to drive it. They are efficient by design.
I'm sure for small scale - but for anything large scale it would require substantial, constant power source. There's no ways a laser with even a simple battery pack is going to destroy entire neighbourhoods