Apart from acting as a filter it's also a way to show determination. If you really wanted to fly for QF but didn't have the educational requirements then doing a year 12 Maths/Physics bridging course is a way to show your desire for the role. Don't complain if you don't, plenty of people who didn't meet the educational requirements in the past have been proactive and completed bridging courses in order to meet the minimum standards.
And let's be honest, almost all other professions these days require a degree (and many graduates aren't getting far in their careers in a lot of areas unless they have done post graduate study) so for a position with such a high level of responsibility a year 12 education should be an ABSOLUTE minimum.