Well, I never the first article (because of the broken link), but the second article jumps to conclusions, that hundreds before him did what he apparently did: give his fully-enabled keys to the valet.
I have a valet key for my car, and that's what I always give to a valet. It doesn't give full access to the car, and I think it'd make it a bit less valuable to have the valet take off with the car. (Not that my Honda Civic is remotely worth anything like the car that went missing here, but it is on the list of the most-stolen cars in the country, which I don't think the Porsche Panamera is on.)