“Why is it called ‘after dark’ when it really is ‘after light’?”

“Why is it called ‘after dark’ when it really is ‘after light’?” is a one-line saying that has been printed on many images. The saying, along with other “why” questions, was posted on the newsgroup alt.basement.graveyard on August 14, 1998.
 
“After dark” can probably be better explained as “after it becomes dark.”
 
           
Google Groups: alt.basement.graveyard
why
BigDaddy
8/14/98
(...)
Why is it called ‘after dark’, when it is really after light?
 
9 December 1999, Machine Design (Cleveland, OH), “Food for thought—part 2,” pg. 194:
Why is it called “after dark” when it is really after light?
   
10 December 1999, Vancouver (BC) Sun, :City limits,” pg. B5:
Why is it called “after dark” when it really is “after light” ?
   
Google Books
Yada, Yada, Yada.Com.Org.Edu.Gov.Email:
What I Learned on the WWW/Internet

By Joan E. Miller
San Jose, CA: Writers Club Press
2000
Pg. 33:
Why is it called “after dark” when it really is “after light”?
 
Twitter
Just Do It!‏
@YoursTrulyXXOO
Why is it called “after dark” when it really is “after light”????  xxoo
12:53 AM - 1 Aug 2008
 
Google Books
The Official Best of the Net Joke Book, Book 2
By Tom Haran, III
Minneapolis, MN: Mill City Press, Inc.
2011
Pg. 213:
Why is it called “after dark” when it really is “after light”?
     
Google Books
Your Brain On Nature:
The Science of Nature’s Influence on Your Health, Happiness, and Vitality

By Eva M. Selhub, MD and Alan C. Logan, MD
Mississauga, ON:John Wiley & Sons Canada, Ltd.
2012
Pg. 91:
Why is it called “after dark” when it really is “after light”? —George Carlin
 
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Consultant LifeCoach Rob‏
@Rob_Rory_Mason
Why is it called ‘after dark’ when it really is ‘after light’? #quote
6:06 AM - 10 Feb 2018