Think I might try to add something to this discussion, based on my own experiences...
I went to an outer-suburban public school which was (and is) known for excellence in extra-curricular activities such as music, art and oddly enough, volleyball - despite being academically very average. Also, it's very progressive (no uniform) and filled with a high proportion of kids with very lazy attitudes - although my year level did possess several high-achieving students too.
Yet my school's teachers - in particular the ones I had in year 12 - were very capable and dedicated to their jobs. I really, really liked my school and when I finished VCE, was proud to have achieved our school's highest ATAR in years. Without hesitation, I would say that I couldn't have asked for a better school to finish VCE at. I shouldn't need to, but I feel I should clarify that I am non-Asian, played quite a lot of sport during the year and attended plenty of 18ths even in the months building up to exams, so I wasn't a hermit

The main flaw, though, was our poor academic environment. Most of the people I mixed with at school were higher achievers than the norm at my school, which helped - but I sometimes felt that my English result would have been better if the other students in my class were stronger, so the teacher could teach to a higher standard. I feel that English, especially, is a subject which is dominated in elite schools for this reason. Another problem - which the OP mentioned - is that many at my school don't believe they can do well, because "we never get good results". You can guess how these types perform.
Although, I would have strongly disliked having rigid uniform regulations imposed on me, so my school suited me well. I loved wearing whatever the f**k I wanted to school. But at the end of the day, horses for courses.