How the fuck did the SCOTUS get it so wrong? This is exactly what the "Establishment Clause" was meant to prevent
Well duh. Anyone who ever played high school sports knows perfectly well the power coaches have over players and how easily the players are coerced into going along with whatever program or religion or whatever personal cause the coach may choose to promote thru the team. The only time that players have the power to defy the coach and still stay on the team is when there is a player revolt against the coach, but that is something very hard to organize and pull off when the team players are always more or less in competition with each other for playing time and starting positions on the team. High school players are too emotionally immature and young to achieve the kind of solidarity and cooperation to pull off a revolt against the coach, which is why the only player revolts I have ever heard of that were successful against a coach were at the college level.
I was lucky that I played sports like swimming and track, where it was all ruled by the stopwatch and the fastest team members got the top spots in the lineup, but I also played basketball in lower grades and it was obvious in those more subjective sports like that how easy it was for coaches to play favorites regardless of ability and talent.