the all state class A/AA is as you say picking 15- girls which is less than 1% of the players in the state in the classification, what you did not mention is that if a coach is not a member of the THSSCA, their players are not eligible to be picked. So in reality that automatically eliminates a chunk of players from selection, especially at the smaller schools whose coaches may not be members.
Also, the last few years before this year, as i was told by a local coach, 14 of the spots were reserved for players of teams that make the state tournament with the last spots going to players on teams not at the state tournament. so 14 players from 8 teams are chosen, and roughly 4-8 players from the reaming 142 schools were picked. so if you lost in the first round of state you got 1 guarantee player on the team, semifinal losers got 2 spots, and you got 3 if you made the final. the remaining 4-8 spots could also come from those teams but not guaranteed.
This year she said that a list of nominated players was sent out for member coaches to vote on, but she was not sent anything about nominating players from her team even though she was a member of the coaches association.
it seems like a small group of coaches running the coaches association set up the all state team to benefit their teams chances of getting players on it.