One thing that hasn't been mentioned yet is the differing expectations of time for promotion. Qantas has been 20 years to command until very recently, slowly dropping back toward the long term expectation of 15 years. There were many (around 10%) that took a leave of absence to gain a command or an FO upgrade in the Middle East & Asia. Many junior QF longhaul pilots genuinely faced the prospect of redundancy for many years
Time to command in Jetstar when growth was ramping up? Five years, and certainly less than ten years. Getting to the LHS of a at least an A320 / B737 provides career protection that an FO or SO doesn't have.
Very few are complaining that they are the LHS when some of their ab initio training buddies are only just a window seat.
Everything is a tradeoff, there is always a price to pay. You can have rapid promotion or terms and conditions, but you can't have both.