Tri-county fire of Labor Day 2011 started from a BBQ. 22,000 acres, homes and evacuations later it was finally out.
Try to find who started it. Try to find who was prosecuted. Nobody.
Try to find who the arsonist kids were who started fires during the big fire. You will find nobody.
We know where it started but not who.
they dont really prosecute these things aggressively anyway, consider this example. This article sure sugar coats it compared to witness testimony : http://www.oregonlive.com/wildfires/index.ssf/2017/11/mortified_mom_of_teen_charged_in_eagle_creek_fire_speaks_this_is_a_trauma_for_him.html