its possible that a previous owner has put some tape over the bulb inside or otherwise disabled it to get it to pass a MOT
if you have an logged fault code then I'd trust that and try and resolve it
some MOT garages will pick up on the lack of the bulb check illumination and fail you - others may miss it
thats possible but would need a custom ECU flash to do so
if the car has been tuned or modified then this might be part of it
what are you trying to achieve?
to return it all to standard ?
what is the fault code / s that you can read off with the scan tool ?