A simpler solution to all these ticketing systems is just to make public transport free. We already have taxes at all geography levels if we want it to be paid by a given city or region. People that don't use it benefit from it anyway by having less congestion in their private transport. Touristy cities already charge a fee per night to pay for the services tourists use. There's no point running these complex billing systems. Save that money to invest in the transport itself.