Suppose a car that is started is parked and locked, with the keys inside the car with the driver. Should someone be able to unlock the car by using the outside buttons on the door? When I try to do so in my 2008 Altima, the system unlocks the door just like it would if the keys were outside. Isn't this a little dangerous from a security point of view as essentially your car is never locked when you are in it.
Not all cars do this. I have personal experience with a 2011 Dodge Journey which uses keyless entry. When I pull the handle with the keys on me, the door automatically unlocks and it opens. However, if I try to open the locked door with the keys inside of the car... it won't open.
I'm not sure how that works, if the sensor is short range and only directed to the exterior or what, but it seems pretty secure as far as that goes given the fact that I can manage to lock myself out.
Different cars are built differently, some are more secure than others in terms of this. But ignoring security for a second here, at least you're unlikely to get locked out of your car depending on where the keys were sitting in the car.