They add instructions.
Like on this ticket punch:
|"Insert tickets as shown in the picture"|
They added instructions because people probably inserted the ticket in the wrong direction too many times, got frustrated, caused stress to others.. but are they wrong? Or rather there's something wrong in the system?
Let's have a look at tickets: a public transport ticket in Milan (the one for the ticket punch above) and a train ticket.
As far as I remember, tickets have always had a "complex" body, with colors, graphics and information and a small empty and usually whitish space on one side. That was the part you had to stamp (the top part in the train ticket).
Clearly the public transport ticket is designed following opposite rules, for the white band is the bottom of the ticket.
Is it still strange that people make mistakes when using them?