It doesn't go off due to someone trying to open the door with the handle (thank goodness) - no one can break into a car by doing that, and who wants their alarm going off every time the passenger jumps the gun and tries to open the door before you hit the unlock?
It only goes off if someone were to break the window or force it with a jim and open the door from inside, which is how car thieves actually break into cars.
A perimeter alarm is the kind that annoys the entire neighborhood in the night because a passing squirrel triggered it, and no one pays attention to anyway.
In fact I would love to be able to disable the panic button on the fob, hit it accidentally in the dark once and really pissed off a neighbor. Is there a way to turn it off?