My car works that way too, except it only unlocks the side you're on at first. For example, as a driver, I can only unlock my side, and then a second unlock attempt unlocks my whole car. It's a safety thing - that way in a dark parking lot someone else can't hop in your car with you, etc.
As a female traveler who frequently travels alone, that makes me uncomfortable. There's been times where I've hurried to my room because someone has seemed a little "off" nearby. I don't like the idea of someone else possibly being able to open my door before I get to it, etc. Seems like a security risk. I'm sure they have thought of work-arounds though... it's too easy to see the security issues.