There are different types of thieves in the market.
1 - small time Mehran thief - simple job to get in and install a new ignition switch to the wiring.
2 - a little pro - has got some nice tools to enter a locked car and disarm a tracker - they do not target cars with immobilisers
3 - pros - they have got key makers with them (usually informed by locksmiths) - they disarm the main battery and jam the tracking unit.
4 - Goons - they will even tow your car away (have seen that happen) - they come with a truck and forklift or a chain type loader. They even do it in broad daylight.