I used to work shifts at a petrol station in my 20s. Just a suburban outlet on the edge of a happy, crime-free modern housing estate in a run of the mill southern town. Crime I experienced included:
drunks falling out of taxis, peeing on the forecourt, throwing up on someone else's bonnet, ruckus ensued..
fisticuffs between taxi drivers and passengers ..
HOW many people lighting up mid-pump! They thyink, "Hm, the petrol's inside this pipe, it's not going to catch fire". They forget the fumes are what catch fire.
A custody battle family doing the weekend changeover and having a massive barney, then the one dropping off whizzing off without the kids, having also taken mum's keys, leaving them all stranded..
Lots of drive-offs, people deliberatley or forgetfully not paying for thier petrol then burning rubber into the sunset..
Schoolkids on mopeds forgettting to brake as they speed onto the forecourt - nasty!
School run stressed mums forgetting to belt the children in their seats in the first place, never mind putting the handbrake on before filling up..
I can't think why complacency rules on this issue, who's to say inner city forecourts aren't just as attractive to criminals as rural ones, think about it...
Especially since the really stupid idea of allowing franchised shops onto the forecourt, meaning alcohol and fastfood licences are granged, encouraging loiterers.
DO google to find recent examples of carjacking, child abductions, etc, THIS YEAR in UK petrol stations, then re-consider leaving your kids unlocked in the car 
www.autoweb.co.uk/article/615