My view is that any incident should be reported but I have found that certain ones have not been due to self preservation. Also incidents, as you well know, can be caused by many different factors which need to be rectified to prevent further incidents.
As far as I'm aware SMF is not at all units therefore some incidents will not be seen nor reported. From what I remember when working ATC the MATS Pt 1 states that all incidents should be reported. I just think that at the moment certain ones are not reported.