In almost all fanon I see scootaloo going on and on about his lack of flight. (And sweetie belles lack of magic) but I keep searching through the canon and there is nothing there.
We know Scootaloo can at least hover with her hooves dragging on the ground and propel herself forward while doing so. Other than that, though, she hasn't been seen flying. In Hurricane Fluttershy, Rumble is seen flying, and he's similarly sized to Scootaloo. Personally, I like to think that her wing cross-section just isn't large enough to generate lift, but her wings will catch up with the rest of her body eventually. It's really ambiguous, though, and there's not much evidence to support any theories on the matter.
My theory has always been that she has the power to fly, but hasn't quite figured how to use her wing strength correctly because she's either too impatient or doesn't care enough.
My theory is that scoots could fly but prefers her scooter.
She does get around just fine without actually flying flying; we know she's not acrophobic, so my best guess is that she just doesn't care to fly around everywhere. Hell, even Dash mostly stays at ground-level and just flies to move faster than she could while walking.
Can you think inside the chimney?
ok

she has the physical ablity to fly, she just hasn't bothered to take the time to learn how. reason other pegasi her age all learned was the ones we've seen grew up in Cloudsdale or another pegasi cloud city and so HAD to learn ASAP to be able to get anywhere, as well as being able to go to flight camp.
Build a fool proof system, and the world will create a better fool.
Yeah, that's the thing. She was born in Ponyville, which is entirely built for earth ponies. She doesn't have to know how to fly to get everywhere, and it's not really what she's interested in, so she hasn't bothered learning yet. Makes perfect sense to me.
Can you think inside the chimney?
Uh, Lurker? Roid Pony has tinier wings in proportion to the rest of 'im, and HE can fly.
Which is why we're attributing her lack of flight to her not taking the time to learn rather than physical inability.
Maybe Scoots hasn't mastered that part of her racial magic yet.
When you think about it, the main pegasis (Fluttershy, Rainbow, and Scootaloo) are really the only characters that doesn't have any know family members.
Pretty much everyone else can fly except Scootaloo, regardless of age or wing size.
If there is anything that you are alone in thinking, it's "thinking that you're alone in thinking of your theories".