I build intercity coach systems that still tell the truth in a ghat section with no signal and on the busiest night after Diwali.
The first fault I was trusted to fix alone was a ticket machine that had stopped printing somewhere between Dewas and Ujjain. I had joined Ojasvel Electronics in Indore in July 2000, a month after completing a degree in electronics and telecommunication at Revakhand Institute of Engineering. The conductor had written tickets by hand for the rest of the journey, and the owner wanted to know whether the machine's count or the conductor's book was right. Neither was complete. Over three years of service visits to bus stands across western Madhya Pradesh, I learnt that a device's record is only as good as what happens to it when power, paper or patience runs out.
A record made in a moving vehicle will sometimes be incomplete. I would rather show that gap to the person relying on the record than hide it behind a confident map or a tidy total. Systems earn trust when the people who live with them have argued about their rules first, and when every number that touches pay, a passenger's seat or a compliance document states how it can be wrong.