Nearly all gas (petrol) stations in the UK are self serve, fill up then walk to kiosk to pay, some give the option to use a credit/debit card at the pump.
There are a lot of drive off cases, non payers, a popular method is to steal number plates fit them to the car temporary, fill up, drive off, remove false plates for next time.
I am in New Jersey right now where it is illegal to fill your own vehicle, I would imagine drive offs are rare here, perhaps a NJ member could tell us.