Why do the names of all passenger have to be entered on the day ticket for Germany?

The regional day ticket or day ticket for Germany are available to individuals and groups who want to travel through a federal state for one day at a low price. You may not resell or give away a used ticket.

That is why a regional day ticket or a day ticket for Germany is only valid if the surnames and first names of all persons travelling are entered on the ticket. Passengers boarding during the journey must enter their surname and first name on the ticket immediately after boarding.

Enter the names as described below:

For tickets purchased at DB travel centres and DB agencies:
The first person writes their name in the designated line on the front side
The passengers write their names on the back

For tickets purchased online and issued as an online ticket:
The names of all passengers must be indicated when booking

For tickets purchased at a DB ticket machine:
All passengers enter their names in the designated lines

For tickets purchased from a cooperating transport company (e.g. on the bus):
All passengers enter their names at a suitable place on the front or back of the ticket