How car a car be stolen without immobilising it

[Chuck Norris]

My 1999 box standard, mitsubishi lancer was stolen. I want to know how the thieves manages to do it without immobilising it.?
I immobilised the car myself a few months back by trying to start the car with a copied key that wasn't chipped so the immobiliser wasn't faulty yet how did these guys do it. The only damage to the car was a broken window to gain entry.
Did the mechanics that fixed the car when i immobilised it do shoddy repairs?

[furrycheeky]

There has been a spate of thefts near recently. 1 broken window, release of handbrake and a tow away for them to work on starting it later.