It looks like Toyota Pakistan is not using the more secure and expensive option of having the Immobilizer chip seperate from the main ECU/ECM of the car which is in engine bay. So in case of Pakistani Corollas, someone swapping the engine bay ECU/ECM will enable them to start the car. Whereas the more modern variant, which has been a standard since a decade or more on JDM cars etc. is a seperate ECU/ECM for Immobilizer chip which is deep inside the dashboard and cannot be replaced easily.
So incase of JDMs, even if you replace the engine bay computer, it won't let the car start.
