Someone asked Lauren
on Deviantart why Scoot can't fly yet, since young RD was noticably ahead of Scoot's progress, and Lauren responded "No reason. She just hasn't figured it out yet." Lauren also mentioned
on Twitter that in her head, Scoot used to be bullied and get into fights over her inability to fly.
The linked interview is a secondhand account of a conversation, and it says "technically handicapped, for lack of a better word". It also goes into themes of Scoot wishing she was someone like RD, and having to come to terms with the fact that she's not.
I believe that in Lauren's vision, young RD was very far ahead of the curve in terms of flying ability, and young Scootaloo is currently very far behind the curve. Scootaloo wants to fly, but that won't happen until she grows up some more, and no amount of wishing will make it happen any sooner than nature intended, not even if nature was kinder to someone like Rainbow Dash. Scootaloo "won't fly" (in Lauren's show) because it's in her character to
want something, not to get it. She needs to learn to let go and enjoy other things in the meantime.
I think that fan image of a grown-up Scootaloo as an eventual Wonderbolt is very touching and appropriate, but the show is unlikely to go that far into the future, which is kind of the point.
After that interview, fan theory got all creepy into "Oh, Scootaloo's disabled? I think her wings were crushed in the birth canal, come to me, my Scootaloo, and I will hug your pain away" and I think Meghan's show should back very far away from those people.
