Sometimes manufacturers overlook items and that is when common sense takes over as in the case of this locomotive's driver's seat. I came across two such items on the A320 during my 8 years spent on the type. The saying that "if it is not in the MEL then it is a NO GO item" is not strictly accurate.
The NEF program (non essential for flight) or basically non airworthy items. Working for a pax airline in the past I had to be careful reviewing our "cabin discrepancy log" that was filled out by FA's. Sometimes emergency equipment would end up in the log. This list could grow long and I actually had a flight crew transcribe the whole damb thing into the logbook once. It was in our program to maintain a running cabin log, it would be addressed at base with ought having to fix or NEF said items in the meantime. Once in the logbook, hell I still have a cramp in my right hand from having to defer all the items.