I think thieves don't want to take unneeded risks. Otherwise, no protection would make any sense and we could as well just leave the doors open. Even if 9 out of 10 times the alarm going off wouldn't be noticed, the remaining chance could still discourage some thieves and make them run away.
Actually that has happened once to my parents' car. The alarm saved the wheels. Thieves wanted to steal the wheels (not the whole car) and they managed to unscrew 3 of them when they accidentally activated the alarm and ran away. Funny, they left their car jack behind.
Anyway, it is a pity they didn't analyze the security level of the OBD2 interface and other systems connected to the ECU or CAN bus. I saw a few youtube videos of thieves stealing cars in a way they enter into a car and in a few minutes they just switch the engine on and drive away. From the outside, it really doesn't look suspicious - probably most people seeing this would not notice the car was being stolen. This shouldn't be that easy - there's certainly something wrong with the design of the factory anti-theft systems.
That's the difference between professional and amateur thieves. Professionals don't give a crap about the alarm because they would have all of the wheels off and gone before anybody could respond anyway.
"they would have all of the wheels off and gone before anybody could respond anyway."
I wouldn't be so sure about it. I heard stories (directly from friends, not only from the Internet) about thieves being stopped by a custom / non-standard / less known protection installed in a car. A thing that the thief does not know in advance and has to first figure out how to crack it. If the alarm goes off, it gives less time to crack the other security systems.
It's partly a bad UX choice by the automakers - as a user, the driver wants to lock their car when they get out. But the car will only let them do that if they arm the alarm with the same action, on 90% of all cars made in the last decade.
I see no problem with that. There's no scenario I can think of where I want the car locked but don't want the alarm engaged.
Part of the problem is just plain oversensitivity (alarms being set off by passing trucks and such), and part of it is bad design. For example, my alarm will go off if you close the trunk. That's completely nonsensical: when the car is secure, the truck will already be closed, and opening it would be the appropriate trigger. But it does mean that I occasionally set it off in my garage because I left the trunk open, locked the car, then came back and closed it.
FWIW there are times when you want to secure the car but have a mobile participant inside the car (and the car has interior sensors that detect movement). Pets and small children come to mind. There are cases (such as filling up at a petrol/gas station) where you want to secure them temporarily in the vehicle while paying but don't want movement setting it off.
Actually that has happened once to my parents' car. The alarm saved the wheels. Thieves wanted to steal the wheels (not the whole car) and they managed to unscrew 3 of them when they accidentally activated the alarm and ran away. Funny, they left their car jack behind.
Anyway, it is a pity they didn't analyze the security level of the OBD2 interface and other systems connected to the ECU or CAN bus. I saw a few youtube videos of thieves stealing cars in a way they enter into a car and in a few minutes they just switch the engine on and drive away. From the outside, it really doesn't look suspicious - probably most people seeing this would not notice the car was being stolen. This shouldn't be that easy - there's certainly something wrong with the design of the factory anti-theft systems.