Do mother and daughter love drilling, or do they love racing? They aren't the same thing. I think they love racing, and simply work, ski drills amongst other things, to achieve that. What is special is the common love for racing between parent and child, and the love for learning. Those who have that, it wouldn't matter if the child makes the USST, much less NCAA. So, for those that dropped out because they feel they can't match MS, they were in it for the wrong reasons.
If you look at how she limited her races when younger, and also how she limited herself to slalom when she started on the WC, I suspect she enjoys drills more than racing! Well, let me clarify a bit. IMHO she likes drilling to put herself into a position to win. A lot (most?) of us race for the adrenaline drive and to challenge ourselves. MS never comes across to me as doing it for fun/a rush or anything other than validating that she is better through her training regime. The difference between her and the other girls on the podium at the SQuaw WC races in the media room was huge. fun does not really seem to be in her vocabulary. Everything is controlled to the nth degree.
I see similar things with some of my masters athletes. They train endlessly looking to improve technique and plan to enter races when they think they have got it down to perfection. However when they are in the cours they just struggle to push it and take the necessary risks. The rest of us are driven by the rush of adrenaline and realize that race results are determined by the clock rather than style points. Not necessarily correct either wAy of course