It’s a safety feature that has been built in, for a while now on most modern cars.
It can offer the driver some protection from other doors being opened, from the outside when you are waiting in a traffic jam in town for example.
Plenty of examples of personal items being snatched from the back seat of car while cueing in traffic etc.
Not sure why you would want to disable it tbh.
The driver usually has the ability to unlock all of the doors manually, via the door switch on the drivers door, on most previous MG models at least.