If you dump gasoline and light it be sure to have someone a safe distance away who can catch you and extinguish your flames. Gasoline vapors will explode, duh.
Lighter fluid, diesel fuel, or kerosene would be much safer. You can safely put a match to them without getting those painful skin grafts at the hospital (BTW, B & W Salve heals nasty burns at home, without skin grafts, quickly with no pain and no scars).
I have found that permethrin (same stuff I use on my animals) kills wasps very quickly when I spray it on them. I would rather use petroleum products and flames for a nest in the ground
As far as the exterminators being better for the environment, I doubt it, it’s just different stuff and more expensive than what you do yourself.
Make sure you do your exterminating at night when they are sleeping in the nest.