As mentioned above, we are only talking about making things unambiguous from a human perspective on a paper ticket with limited space\information.
It's also going to be very useful when talking to a human agent on the phone.
The computer systems were designed to automate the existing paper systems.
Any computer system written from scratch would have let you book a ticket any time until 31st December 1999, 18th January 2038, or some time after the end of the universe depending on the design choices prevalent at the time.
As with most things, it's not a computer problem, it's a people problem.