How long ago did this begin happening? My youngest graduated h.s. in 2005. Certainly she and her sister did not spend their h.s. time that way.
I'd like to see grade schools, at least, try this idea. First, get rid of some of that burdensome admin staff. Then get rid of the one teacher/25 student thing. Hire paraprofessionals and do a team-teaching approach. The students would be divided into small groups and paired with a teaching assistant who could give more individualized instruction based on what the students' level is. This could be a fluid system where students could move between levels as warranted. The teacher would be responsible for curriculum and lesson plans, oversight of the assistants, and testing. Even if only implemented up to grade five or six, I think this would be a much better way to teach then the one-size-fits-all current system.