Minor characters get pages if they physically appear and are not part of a crowd (e.g. the riots from Cases 50, 52, 54) or if they have an important bearing on the case. Some exceptions include the unnamed sorority founder who's... there
Organizations only get pages if they're important to the story. Exception to this is The Skulls and The Vipers pages, which were long-established before editing standards were set in place here and therefore would take too much housekeeping if deleted.
Minor characters get pages if they have an important bearing on the case.
All three of those characters are the basis of entire legs of the Additional Investigation in their cases (Out of Breath, Overkill, and Day of the Dead respectively). Arturo and Eduardo are the children of main characters. The latter is the entire reason behind Ingrid's personality. Wharton tried to marry Maddie so he's important too.