I don't understand the reason for having Gas & Power vehicles, when the company providing the power/gas would be the ones who respond to disable / neutralize it. I think it was already mentioned that anything that's not related to Fire/Police/EMS would not be added, as it deviates from the actual point of the game.
The reason for gas and power vehicles is when a call like a house fire or gas leak would come in the fire chief or first in crew would call for power or gas to shut off lines so they can work safely. kinda like towing fire department or police department will call a towing company (some fire departments have roll back tow trucks) to tow cars away they dont get the call right way but they do come out and help them.