Self-appointed volunteers are better at generating leads for real investigators. “Capturing evidence” is not a role for civilians.
Police, sheriff, and fire agencies have trained professional investigators. I’ve interviewed a handful of law enforcement, fire, and search and rescue air team members, NONE of them want untrained people involved in emergency response operations.
Many search and rescue teams are staffed by volunteers, and welcome new people, including drone pilots. It starts with training in SAR, because everyone needs to know the operation, before joining any specialized teams like aerial search.
Emergency response has a strict command structure because without it untrained volunteers frequently become casualties needing rescue themselves. Everyone involved is very intolerant of people getting in the way of their vital mission. They own the airspace in fire events, it officially becomes controlled airspace. Stay out.
And, yes, some wildfires start “naturally” with lightning strikes.