When i got my Y2K last Dec., there was no "key" for the stock locks. The dealer said that they had to drill them out!?(NOT) A little (I mean very little) internet research revealed that there is a "twist" socket that removes it easy as pie!!! - and it's pretty cheap to buy. I also found out on another forum the company that made the locks and i went through a procedure to get a new key for $19 which is where i went.
That said it was noted on the blogs that with the "twist" sockets out there, that GM stopped using the locks to save money on a useless product. To sum it up the owner and the shops are inconvenienced while the thieves are well prepared.
Any lock has to be secure yet servicable.
To my mind the best solution would be a sensor in the fender well that senses the presence of fat little fingers and triggers the alarm!! Easy enough ----- work on it.
New(old) thought - I forgot an oldie that was quite effective. A motion sensor on your alarm. if someone jacks up the car it goes off.