Keys are over-engineered.
My Hyundai Sonata will lock all four doors by itself if a key is left inside of it. I actually leave one of my two keys inside the vehicle continuously for convenience. I took my car into the service center about this concern, and it turns out that this is a known issue. I have only managed to allow my car to lock me out with my keys inside one time so far, although I have to admit that this is a huge inconvenience for me, and a complete undue stressor. There is no reason for a car door to lock when I am standing right beside it. My concern would be if I have a baby or an animal in my car, I step outside for one second to speak to someone, or return a shopping cart. It would be endangering the child or pet to be locked in the car until help could arrive.
Also...even though the key will lock the car doors randomly when I do not wish it to, I attempted to leave my car running with the AC on, on a scorching hot day to cool the car off before I had to get into a 120-degree car. I tried to lock the doors with my second key fab, and this fab is completely disabled while the car is running. I was totally unable to cool off my car and secure it from theft simultaneously. Again, I can see this being a much bigger issue in the north when people frequently have to warm up their vehicles for 15-20 min. everyday. How are they supposed to be sure someone does not steal their car in that period of time if they are unable to lock it?