@Mr_NutterButter @xianc78 blue lasers are the most powerful for destruction if I'm not mistaken. Or, they're the easiest to make very powerful. Something like that. I'm no scientist but my educated guess is that the higher up on the color spectrum you go, the more damaging it is. Blue light probably has a good balance of efficiency to destruction. Blue light can be destructive to your eyes, even if temporarily, and something like UV is obviously a lot worse considering it can damage your skin. But it's probably a lot harder to make a "UV laser" or whatever the equivalent would be. A UV laser probably needs a lot more cooling, bigger chassis, and might be overkill for the purpose of setting a house on fire or something.
All conjecture, not 100% sure, but I am a casual laser enjoyer.
@Mr_NutterButter @xianc78 it's also possible that something like a UV laser would be a lot more noticeable. the effects of it. for now, with a blue laser, all we can really do is say "the buildings with blue rooves are unaffected" but it gets quite into conspiracy theory territory. with a UV laser, it has the potential to interact with a lot more stuff and would likely be easier to say "this is definitely a laser."