Paul Chiddicks recently wrote an insightful post about separating truth from error on official documents like birth, marriage, and death certificates. Sometimes ancestors didn't know, sometimes they didn't want to tell, sometimes they flat-out made mistakes or omissions when providing information to authorities.
Case in point: My 3c1r Milton Weiss (1920-1995) enlisted in the US Army on January 29, 1942, to serve in World War II. (He was honorably discharged in December of 1945.)
On February 15, 1942, he and his bride-to-be, Charlotte Schnee (1926-2000), filled out a marriage license application in Manhattan, New York.
At top, you can see that bride and groom each printed the information on the application. I always look at an original document if available, rather than any transcription or index. Happily, New York City makes these originals available! I found this on MyHeritage.
Charlotte herself wrote that her father's name was Morris A. Schne.
Whether the bride was nervous or in a hurry, I can't tell--but she certainly knew her father's surname because it was exactly like her own, as I know from looking at other official family documents.
Interestingly, when the New York City clerk typed up the info for the marriage license, based on the hand-written application, the clerk ignored Charlotte's mistake and simply typed her father's name as "Morris" with the assumption that the father and daughter shared the same surname. Correct, though not an accurate transcription of the application hand-printed by the bride.
Charlotte and Milton were married for more than 50 years and had two daughters together. Finding this handwritten application reminded me that even an informed informant like Charlotte can make a mistake.