Please provide proof they are all sequels rather than simply films set in the same universe.

How would one prove that? I don’t see why they aren’t considered a collection just because it has an unorthodox style. They’re are recurring characters and reconstructions of each previous film. These films are a trilogy.

 There are films grouped as collections already on TMDb that are not "sequels,"

Please report them (Overview -> Report)

A collection shouldn’t be based on whether they are sequels or not, but the Koker trilogy definitely qualifies as sequels. Anyone who has seen the movies would agree. The definition of a sequel is as follows: “a published, broadcast, or recorded work that continues the story or develops the theme of an earlier one.” Or “something that takes place after or as a result of an earlier event.” The first movie is about a young boy trying to find his friends house. The second movie is about the director of that movie (not the real director, the real director (Abbas Kiarostami) directed all of the Koker movies) visiting Koker after a devastating earthquake. He looks for the boy just as the boy looked for his friends house; meeting new people and having a grand adventure. I would say that counts as developing themes. The third movie is about a specific shot from the second movie and how long it took to get it. This movie casts a new director to play Kiarostami and tells us that the second movie was just as “fake” as the first. These movies would make zero sense without knowing the background behind the others. They have repeating characters, scene callbacks, and the same setting. They all deal with human connection, Camaraderie, authority, and some sense of meta. If you haven’t watched these films I highly suggest you do, and if you have I would love to hear why they aren’t sequels.

Yes, I second this! These three movies better fit the definition of a collection (recurring characters for a start) than some groupings on here like the Three Colours or the Ang Lee collections (which I don't want to see gone, I just want the Koker trilogy to get Collection recognition).