The only reason people use propane is because there is not a natural gas line running in front of their house. Propane is more expensive. If you live in town, you use natural gas. If you live outside of town and there is no natural gas line, you have to use propane, or electricity which is more expensive than propane.
Economics drives Everything; eventually.
We use gasoline in most all vehicles, then diesel (which is almost identical to fuel oil) then CNG/propane then electric.
I’d like to see a chart of the cost per BTU of each type of fuel:
Wood,
NG,
propane,
coal,
electricity...