Overhead a nice ticket inspector giving some friendly advice ".. the amount of people whose phones are flat for their return journey, and they have to buy another ticket".
Nice little earner for Greater Anglia. Encourage the adoption of electronic ticketing & reduce the availability of hard copy tickets, and you get to overcharge afresh at full rate. May also explain the lack of proper functionality of on-train charging points.
Is a simple list of names of paid-up passengers too much?