Question about Flexible Sync operators

In the Flexible Sync Permissions Guide, the Restricted News Feed use case uses the $in operator to allow permissions to any value in an array:


But in what seems to me to be an analogous scenario in the Dynamic Collaboration use case, where I was expecting to also see the $in operator, it is not used:


So I can better understand how this all works, can someone explain the distinction between the rule constructions of these two use cases? Thanks!

@Ian_Ward perhaps? :pray: