[pkolaczk]

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.

[jandrese]

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.

[pkolaczk]

"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.