I think it comes down to context usually. When speaking casually with others about the cost of natural gas (which is only available in cities and some towns) we might say something like "gas rates". The word "rates" indicates we're talking about the metered commodity of natural gas. When we talk of "gas prices" we're talking of what you all call "petrol". While the price "at the pump" is technically a "rate" we don't treat it as such.
Additionally natural gas prices are more or less a monopoly, meaning it is what it is, there is no shopping around as it's a hard piped utility. Gasoline obviously is more competitive in communities.
But yeah... context.
To add confusion most rural people like myself who use gas actually use propane, which is also a "gas" and like gasoline is something we can shop around for and not really a "utility" however most people I know just call it "propane".
Any appliance or heater we buy usually has to be field converted from nat to lp gas as the orifices for nat gas are larger than propane... which isn't even a gas when it's in the tank... hence the abbreviation, LP (liquid petroleum), it only turns to gas when opened to atmospheric pressure.
Around here natural gas seems to cost a fraction of what propane runs. Most people just fill 100lb bottles locally and heat with propane space heaters, I myself lease a 250 gallon tank from a local company, they come by and fill it on a "will call" basis.
It has been running about $1000 per year to hear my home, but that cost may go up a bit as I've recently installed a gas (propane) range/oven. That said I imagine my electric bill should decrease somewhat by not using electric cooking means.