Okay, Scoot's wings are just not big enough yet. Looks at Snowflake. Um...

[Frith is Magick 1,471]

It seems that magic is largely agreed upon as a key requirement for flight. Using this assumption, it is possible for ponies like Snowflake to fly despite small wings. A possibility that allows Snowflake and Poundcake to fly, but not Scootaloo is that Scootaloo does not have a sufficient flow of the necessary magic. Perhaps she has a large representation of Earth Ponies in her ancestry, which causes her body to have greater affinity with the ground despite being a Pegasus. It may not count for much, but she has earthy colouration for a Pegasus, lending credence to Earth Pony heritage. Scootaloo's magic may simply be suited for pursuits other than flight. That may change with maturation and training, or it may not, that waits to be seen.

[Never2muchpinkie 211]

It seems that magic is largely agreed upon as a key requirement for flight. Using this assumption, it is possible for ponies like Snowflake to fly despite small wings. A possibility that allows Snowflake and Poundcake to fly, but not Scootaloo is that Scootaloo does not have a sufficient flow of the necessary magic. Perhaps she has a large representation of Earth Ponies in her ancestry, which causes her body to have greater affinity with the ground despite being a Pegasus. It may not count for much, but she has earthy colouration for a Pegasus, lending credence to Earth Pony heritage. Scootaloo's magic may simply be suited for pursuits other than flight. That may change with maturation and training, or it may not, that waits to be seen.

Yeah. In a Rainbow/Scoots fanfic I'm writing, even after she DOES learn to fly, she still mostly sticks to her scooter, simply using her increased wing strength to aid her in her scooter riding and in doing tricks. Mostly because Rainbow encourages her to, telling her to find her own unique way to shine since she, Rainbow, is the best flier ever and she doesn't want Scootaloo to have to stand in her shadow.