Starlight Glimmer has a mild distrust of authority figures. It’s a textbook example of
psychological projection; deep down, she’s still struggling to forgive herself for her own abuses of power.
Celestia has no power in the dream realm and Luna only makes her rounds at night, so if you’re asleep while the sun is up, nopony will be around to help if your nightmares get out of control.
(Warning: s7e13 spoilers) In the Nightmare Moon alternate timeline, Applejack doesn’t live in Ponyville any longer, nor does she go by “Applejack”, and she even has a different cutie mark (which is unusual even as a result of timeline alteration).
Even without the Rainboom, Applejack soon realized that Manehattan did not suit her. The feeling of being “guided home”, however, was notably absent, and the filly remained unsure of her place. This caused her to become curious about her mother’s family, about who they were and why nopony spoke of them. And once she finally managed to get answers, she was determined to connect with the lost side of her heritage, as well as insisting that her mother try to mend fences with the other Pears. The reunion was rough at first, but Grand Pear quickly warmed up to his granddaughter. Not only did Buttercup manage to mend fences somewhat with her family during this visit, but Applejack managed to finally get her cutie mark… which proved problematic, as it wound up being a barrel with three pears on it. Bright Mac still shared his daughter’s joy, but Granny Smith… well, she tried to be fair to the girl, but old grudges die hard, and found she’d often acted on them before she could catch herself. Sadly, Buttercup and Bright Mac’s time soon ran out, at which point “Jackie” was sent to Vanhoover to be raised by her mother’s side of the family, and eventually started going by the name Perry Barrel. She’s basically the same pony, except with a different hat and accent.
Applejack’s absence from Ponyville in that timeline, incidentally, is indirectly responsible for Rainbow Dash’s allegiance to Nightmare Moon. Without Applejack to hold her back, Rainbow Dash was free to attack Nightmare Moon when she first appeared. The battle ended predictably… But not as one-sidedly as you’d think, and Nightmare Moon was impressed with the courage, skill, and sheer
audacity of the little blue pony who’d risen to challenge her. She could have whispered corruption into the mare’s dreams, but instead shy chose to approach her in person, appealing to her pride and her thirst for excitement, and persuading her that it was ultimately Celestia, not Luna, who had truly betrayed her sister. Over several encounters, her sweet lies, her corrupting presence, and Rainbow Dash’s own shortcomings eventually swayed her to the side of darkness.
Vice Principal Luna’s driver’s license photo is a human version of this:
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