US regulators consider doors that remain locked from the inside to be a death trap. That's why that feature is disabled on North American models.

In the UK and other parts of the world, regulators consider the ability to prevent a car thief from simply breaking the driver's window to open the door from the inside to outweigh the risk of someone being trapped inside and unable to open the door to escape.

I don't understand how anyone can value property over life. What am I missing?

 

I would think for the same reason our cars have only one back up light, the one on the left is a fog light, which when lit, shows a bright red, even though it is a white lens like the backup light on the right.
European reasoning is that it is better to be seen, than to see.
It would be more logical, at least to me, that Jaguar in its' design could have done both. At least that is what one would expect in a $70,000 + car.

 

It's to stop someone getting IN to your car by breaking a window and then opening a door from the inside. When the car isn't double-locked that is what happens, so Mr Nasty can smash a window, open the door, steal your stuff from inside the car, or even attempt to bust the steering lock and hotwire it. It's an added safety precaution. It would also mean that if you had locked the car that way, anyone locked inside would be unable to open the door to get out. But that begs the question, unless you have an important role in Fargo, as to why you'd be locking someone inside your car The user manual advises against double locking if there is someone in the car. I also only single lock if I am leaving my dog in the car. There's no downside to having double-locking - you don't have to use it if you don't want to, but if you do then it's there for you. I always double-lock unless my dog is inside the car. I have never felt the need to lock people inside my car Yet.

 

I think that what you may be missing is that the operator has the choice. I can choose to single lock my door (if I want to follow the American concept) or I can double lock my door if I want to follow the UK concept. As I am able to determine easily enough if someone is inside my car when I lock it, I can make the appropriate choice, whereas people in the US are denied that choice. I always prefer choice over no choice.

If the choice didn't exist and the door always double-locked, I'd agree with you that property was being valued over life. But it isn't.