Reading the reports in GASIL it seems to me formal reports only tend to be made when the infringement is blatant?
Not always true old chap. I have been involved in CAA legal action even though the pilot was unaware he was over BUR heading South East at 2400 - thinking he was in the CPT area aiming for Fairoaks.
Not exactly blatant but costly all the same. (about £2000 in this case)
It doesn't help when LHR are breaking stuff off their approach, aircraft hold for 20 mins etc.