A good story needs a beginning, middle, and an end.
Normally, a story has conflict so the beginning is the identification of the conflict, the middle is the steps taken to resolve the conflict, and the end occurs with the solution of the conflict and the effects of the solution.
To have a story without conflict requires a different system of beginning and ending the story.
For example, a character can be born, live a happy life, and die peacefully. Given enough Crowning Moment of Heartwarming
, this can be a very good story with a cathartic ending.
Likewise, slice of life stories tend to be about a character who wakes up in the morning, goes through a normal routine, and then goes to bed at night. The routine elements help to mark the passage of time from beginning to end. The elements of the story don't have to be routine, but there needs to be a little something called "progress" to avoid the feeling that "nothing is happening."
"Nothing happens" is common complaint for stories that don't have a defining conflict such as an antagonist or "villian" to deal with. The fact that many things do happen is apparently not as important as the fact that nothing explodes. However, the real reason conflict stories are more common than non-conflict stories is that they have the ability to reverse progress.
Without time-travel, the events of the day cannot be reversed. However, if the hero takes steps to stop the villian's plan, only to find that the villian was planning something completely different, then all the progress they seemed to be making is lost and they have to start over. This helps to avoid the impression that the reader can tell the rest of the story, and thus loose interest in the author's interpretation of events.