The majority of cars manufactured since early 2000 have had one or more Body Control ECUs which perform all sorts of functions. BMW, Mercedes, VW and some other car makers introduced these before 2000.
Gone are the days when you push a switch that completes an electrical circuit to open a window. These days it is more likely that pushing a switch sends a signal through your car’s Can Bus Network to the Body Control Ecu which then sends a signal to the window control motor which then opens the window.
The reason for this is that it allows such things as automatic window closure when you lock or alarm the car.
The problem is that while all this extra functionality may seem like a good idea when everything is new, as soon as moisture and condensation get into the systems it does not take much to cause all manner of problems