These jobs have natively-available spells that are mostly found in the Scrolls category of the Auction House. All of the magic, with the exception of possible ones, can be purchased from either NPCs or the White Magic and Black Magic subcategories.
These jobs do not share magic with others. They are on this page because they are (for the most part) still spells, and most of them can be learned by purchasing something from the Scrolls category. The exception, of course, is Blue Mage. BLU learns magic from foes only.