Addendum

The secret is that I just wanted to roll out "thaumatocracy."

Against Thaumatocracy

Given that being capable of magic is better than being incapable, what are some reasons mages might not be in charge?

- There aren't enough of them
-- It requires innate talent which few have
-- It takes too long to learn
-- They keep dying
-- Numbers are limited by the need for some external resource. For example a mage has to bathe in dragon's blood or make a contract with a manticore
- There are too many of them. Being a mage isn't a big deal, and hiring some is less of one.
- Magic isn't that good
- The kinds of people who learn magic are bad at maintaining political power
-- They're too busy with magical studies
-- Magic is linked to certain characteristics such as lack of ambition or gullibility
-- Magic alters mages, for example removing the need for food and replacing it with an insatiable urge to visit places of power
-- Magical expenditure requires long periods of isolation or hibernation
- The kinds of people who learn magic don't want to maintain political power
-- Magical talent isn't hereditary. Ensuring your family will be passed over for some genius discovered in a village is distasteful.
- The kinds of people who learn magic can't maintain political power
-- The gods who give them power forbid it
-- The terms of their contracts forbid it
-- The dragons who rule the world forbid it, and they do check regularly
-- Magic circulates through the bonds between people, so that the more subordinates one has, the more his magic is divided among them - The rulers are capable of preventing it
-- They aren't mages, but they have magic
--- Divine sanction
--- The approval of the land itself
--- Contracts with manticores
--- A store of artifacts
--- Hereditary talents
--- They're the source of magic
-- They're above magic
--- Gods rule directly
--- Dragons/manticores/basilisks etc. rule directly
--- Aliens rule directly (they came to research magic)

There are a few reasons. As for how mages might become an oppressed minority, they can't, cut that out, your allegory stinks.

Cutting Things Into Strips Is a Real Hassle

The king on his proud seat received the colonists who were in his land by no arranged plan but rather by the caprice of gales and crashing waves. He listened to their story and made this response.
"If your bravery will hold for another such voyage, I will feed you and outfit you and send you on your way."
"You are a host among hosts and a king among kings," the colonists said. "Is there meaning though in that 'if?'"
The king called his servants to bring to him a chest, pointed out a great hide within it, and had them offer that to the colonists. "If you seek a sure home, you may find it here under my scepter and laws. You may have for your old customs, your former law, and whatever gods you carried hither just so much as you are able to cover with this mffgh." He shoved off the hide the colonists had thrown over him. "Clever, but to own the king is not to own the kingdom."
"We're gonna make you clean the chamber pots."
"I'll give you one-fifth of my kingdom not to do that."
"Deal!"
Finis

Thrilling Space Commerce

"Approaching the destination, Captain."
"Good. Put it on the viewscreen." Before the crew appeared a celestial body unlike any other, a thing of majesty and ancient rites no product of the modern age could contemplate without terror.
"The mummy planet," an officer breathed. The captain suppressed his irritation and spoke calmly.
"You are not to refer to Ferrande 4 as the mummy planet while on this ship," he reminded the crew.
"But sir! It's covered in bandages!" The officer pointed at the screen, as if none of the others had failed to notice the mysterious wrappings that covered every acre of the world and waved in the cosmic wind.
"And when our company's bid to replace those bandages is accepted, we'll all get a comfortable bonus. That will only happen if we don't offend the locals." The captain leaned back. "If there are any," he muttered, for even he was unable to deny his dread of the bizarre planet's secrets. He was, however, able to overlook it so long as there was a payout at the end. But was there? Find out in next week's episode, "It Turns Out the Mummy Planet Is Evil and We Have to Destroy the Core!"
Finis

The Creation of Shadows

Enjoying the Contract Renegotiation Festival? What? You don't think we should have a festival for that, or even allow it? Now, you might not know this, but the gods sanction contract renegotiations by their own example.
Once, Day and Night agreed between themselves to split the guardianship of the world evenly. The creatures, the corn, and the fruit all prospered under their eyes that watched together, though most preferred one or the other.
Then one creature, you know which, discovered the use of fire to repel enfolding Night. That guardian met its obligations less and less, and Day made up the difference. At last, Day called Night to account.
"Do you, then, yield all the Earth to me for all time? Or will you resume the proper execution of your duties?"
"Alas, I cannot do as I did before. However, my half of the work can be done in this way. Now and forever, the creatures, the corn, and the fruit, as well as the rocks and the clay, will cast shadows as my spies during your time that I may lighten your burden as I fear you must mine."
And so Day and Night renegotiated their contract to the good of all the world. In that same spirit, why don't we discuss the two cows someone much like me but younger may or may not owe for services possibly rendered to someone much like you, but less dignified?
Finis