This is really all just designed to minimize impact on canon that could make things hard for potential players down the line, and to make sure that players aren't essentially playing multiple characters with one app. The reason it's "all NPCs" instead of just "appable characters" is that, say, non-appable mascot characters can still be influential in how canon turns out. For example, there are several A.I.s in Otherland which I wouldn't consider appable but which are hugely important in moving along parts of the plot. It's characters with a narrative role that we're looking at, mostly, along with some potentially narrative-shaping actions and interaction with the game. Your random townspeople probably don't have much of a narrative role beyond going "it's a bird! it's a plane! no, it's a magical girl!" Deciding for yourself what the random crowd does isn't going to have enough of a narrative impact there to require permission. And we certainly don't want players to make their homes ghost towns just because the people they would pass on the street are NPCs! Similarly, you're allowed to invent minor NPCs to just show a general part of the world, like the patrons of a bar or random classmates. As long as they don't develop their own narratives that would disrupt the main canon narrative, they're completely fair game.

We also naturally assume that characters are talking frequently to people on their own world, and that's okay. If Masamori wants to mention a report his coworker gave him that reminded him of something on the community, that's assumed to be within the boundaries of daily life and does not involve direct interaction with the community by an NPC, so that's fine. If the coworker is doing a report about the community, or I want to post a video including the coworker, that would require permission. As far as logs go, it's usually find to assume that random members of the group your character is part of are around. It's when you also want to give them speaking roles in the log that you'd need permission, because that's direct interaction with game characters.

Really, we mostly just want players to use common sense and ask themselves "could this effect my characters world/potential canonmates?" If the answer is yes, then you should be asking permission just in case.