You drove and pulled up to the gas station to fill your gas tank. You exited your vehicle, opened your gas tank cover, grabbed and put the dispenser nozzle in. You also had to pay at some point.
How can you forget that the hose is still connected to your car when you drive off?
In all EU countries I drove trough, the pump doesn’t auto-start when you unhook the nozzle from the pump. I think the cashier has to manually allow it to start, from their control system/computer.
So I suspect they glance at clients through the shop’s window/cameras, and they don’t start the pump if you look shady (hooded, no plates on vehicle) and they suspect you may run it off.
For example if you ride a motorbike, the cashier sometimes doesn’t start the pump until you remove your helmet / uncover your face (allowing cameras to see your face).
And yes, after filling-up you then need to go pay at the desk. There can be a waiting line if there are more pumps than open cashdesks.
For these we need to swipe a payment method before the pump starts. It locks a sum on your card, say 200EUR, and when you hook the nozzle back it adjusts the payment transaction to only the amount consumed and debits you.