London Underground's 'Rainbow' software sounds the alarm whenever it spots a 'pattern' of non-attendance. It is quite bad enough that these 'patterns' are often simply coincidences. But what makes matters worse is that they are also picking up on absences for which you should not get even the hint of disciplinary action.
For example, drivers on the Victoria line have had 'rainbow' letters include assaults, one unders and near misses! In a particularly awful case, one driver had his trauma-induced sickness from the 7/7 bombings included.
No wonder staff are coming to the conclusion that LUL operates a very sick system. And no wonder people are voting Yes to action.