Why is it so hard to hire a car?

My passport and driving licence sat on the counter but the girl stared back at me, repeating her demand.

‘I need your DVLA check code,’ she said. I told her I didn’t have the slightest idea what she was on about. ‘I need your DVLA check code,’ she said again, doing her best ‘computer says no’ stare.

The Sixt rental office was in the atrium of the Hilton Hotel Gatwick, which for some reason had been heated to something like sauna temperature. I had walked what felt like a mile, pulling my wheelie suitcase, because Sixt wasn’t in the main car-hire area near the terminal exit, and hadn’t warned me very enthusiastically either, during the booking process, that it was going to be the other side of the multi-storey car park, down a walkway tunnel, and all the way to the far side of the hothouse atrium of the Hilton.