I think it is to force you to pay the full CDW fee, or face the $6000 charge. In North America it is common for people to have the hire car coverage option on their main car. So it becomes a fight between e.g. Hertz and a big insurance firm.

I can't pick up a car in Europe in less than an hour, have to check/photograph everything. I have an actual checklist.

can you share the checklist for us who are curious?

It's just like the one the hire car companies use, front/right/rear/left elevation, roof, windscreen, tyres, side mirrors. Inside: seats, control knobs, petrol gauge, odometer, warning lights. Engine bay: water, washer fluid, oil cap.

The difference is that it's my checklist and I do it, taking the required time. Photographs of every panel. It is inspired by all the times I've been ripped off or they have tried to rip me off.