I know people who have kids in both state schools and private fee paying schools. The people who I personally know with kids in private schools have made their choices not because of discipine or similar, but based upon the school leaving qualifications their kids will gain and the smaller class sizes. Rather than take the NZ NCEA, they would prefer their kids to gain either Cambridge IGCSE's and A Levels, or take the IB. There are a small number of state schools that do Cambridge Exams alongside the NCEA, but they tend to be very over subscribed with tight enrollement zones. It is, however, possible to gain such qualifications via other methods if desired.