"Since 2015, 'Pyongyang Time' has been 30 minutes behind the rest of the Korean Standard Time (KST) zone." (July, 2018 Ivy League Analytical English magazine)
Why does the author use the rest of, not all of in this sentence? According to the Longman Dictionary, the rest means "what is left after everything or everyone else has gone or been used, dealt with, or mentioned." And here is one of its examples, "Does anyone want the rest of this pizza?"
In view of such a definition and my understanding of the word or phrase, I think the use of "the rest of" is a little odd. What do you think?
Thank you so much!