Jetstar staff may be "more engaged" than those of the parent airline. Not surprising, as the transmission of flying has be going on for the last 5 years.
However that does not explain why J* staff attrition has been double that of mainline for the last 5 years.
From the financial report:
Attrition has replaced turnover as a workforce planning statistic and as an indicator of engagement. This is consistant of the new management team's focus on employee engagement.