It's not a 'muck up', it's a system designed to favour the rich...
Because the gap between state and private school 'results' has widened again...
Any system that is set up to only give out a certain percentage of certain grades is open to manipulation and that is what happens...
More civilised countries (many in for example the EU/EEA) tend to have a simpler and more transparent system...
In that grades are awarded based on academic achievement, not by an arbitrary quota!
It's also easier for prospective employers/universities to compare results over different years.
Another stupidity about the UK system is that university places are usually given on a provisional basis rather than the far more logical idea about awarding places based on actual results!
And before the usual suspect chips in again about 'sour grapes', I attended a private school via a scholarship (which no longer exists) for part of my education...
And can thus see both sides of it!