Having done 4 years in hell, er I mean Esso I can tell you the mobile phone thing is to do with attentiveness, the pump cut out is not 100% effective and will sometimes fail.... Result is you covered in petrol and the forecourt covered as well.
You'll also notice that most filling stations are using air conditioning constantly to pressurise the shops so that fumes aren't blown in and allowed to accumulate leading to....
In 4 years I saw it all, cars crashing into pumps, cars on fire being driven onto the forecourt, leaking fuel tanks, idiots smoking, people trying to get their kids to fill cars, one moron during the fuel strikes filling a wheelie bin which promptly melted on his back seat, a guy filling up a milk carton because he didn't want to buy a £3 fuel can (he paid for the pint of milk, the pint of fuel and then got a bollocking for being so stupid!
There's more to being a pump jockey than you think