However, in stories Lois always calls her dad "Daddy".
Ah, Mrs. M, I think you're over-generalizing
You got me. I almost hedged and wrote "usually", but I went for the hyperbole.
I have been digging a bit on this but am having difficulty finding any story here where Lois directly calls Sam anything but Daddy. I as mentioned in the Series and the episode of "Requiem for a Superhero" she directly calls him Dad early when she is trying to keep emotional distance between herself and Sam but later when she abandons that idea she calls him Daddy. I guess it has to do with the relationship the individual author is attempting to convey.
That concept does not bother me because I lived in the South for nearly two decades and the girls/ladies always referred to their father as 'Daddy' even when they were in their 50/60's (the daughter). The kids also always call my wife and I 'Mr Mike' and 'Mrs Cathy' and many of the ones we remain in contact with still call us that to this day and the 'kids' are nearly 40...
Mike