I have always assumed every ticket has unique QR code and could be tracked as it would encode all the data on the ticket.
A standard QR code can store up to 4,296 alphanumeric characters.
If you include all the info from a ticket like date, route no, vehicle no, driver no, machine no, trip ID, ticket no, ticket type, you could do this in less than 50 characters so you are only using just over 1% of the space unless there is built in redundancy with multiple copies of each parameter.
