Actually HT i would blame the problem on the individuals that installed the stereo components in the car, as it would be there fault for not installing the component the proper way.
If it was installed properly then it would not of triggered a fault with the electric solarnoid that controls the locks on the doors...

And if more people experienced this problem with the same model of car, then it could be put back to the manufacture's of that car for not installing compatible devices to support Foreign objects ie: Car stereo's..

Sorry but i think i've grasp the point you were making, so if i'm waaay of the mark then please correct me with this..