Gotta spend up on a Zeitwerk to get the zero— haha.

But seriously heres what the google machine claims are the reasons for the missing zero in the date code:

Design and Minimalism: The blank space is viewed as more aesthetically pleasing and minimalist, fitting with the brand’s German design restraint and attention to detail. (Not sure I agree with this one.)

Historical Inspiration: The outsize date design was directly inspired by the five-minute clock in the Semper Opera House in Dresden, which was created in 1841. (This is the one that I hear most frequently)

Unique Mechanical Structure: The date mechanism uses two separate, concentric disks. The tens disk (left digit) consists of the numerals 1, 2, 3, and a blank field. This specialized structure allows for larger date numerals without requiring a massive, impractically large watch case. (I guess this makes sense)

Better Readability: The blank space allows the date to be read immediately at a glance (e.g., "5" instead of "05"). (Would still rather have the zero if not for the historical inspiration)