A couple tens of thousands of HS's in the nation. In order to consistently be in the say the top 50 or so schools year in and year out, you kinda need most or all of the following:
a large school - very few public schools consistently make NXN/RunningLane/whatever without large enrollment. Sure, some schools have a run of a year or two, but the ones that keep showing up over the span of a decade or more generally have a large athlete pool.
a large team - can't have this without a large pool to draw from. When I say large, I'm talking 75+ kids per gender large.
a strong culture - Freshman Dance above is a perfect example. a coaching staff and upperclassmen who drink the Kool-Aid. There have been PLENTY of professional/private coaches and former Olympians who have had success with world class athletes but simply have not been able to translate that success to the HS level. Much of this ties into understanding and fostering "culture" at the HS level, as even elite HSers are different beasts than post-collegiates.
training that takes advantage of large numbers - look closely at York, Great Oak, Wayzata, etc and you'll see that they have all found ways to leverage their large numbers in a way other schools haven't. If you've only got 12 kids on your team and one of them is an 8:59 guy, it's hard to give everyone what they need in workouts. However, if you've got another 12 sub-10:00 guys, you can get creative and make sure even your best kids are getting what they need by using the next tier of guys creatively.
competent training - doesn't have to be world class but needs to have some thought behind it. this component is not as important as we all want it to be.