Spirit is staffed at roughly 18 pilots to one Airbus. Why do you suppose that is? To support the giant gorilla in the room called their contract. Where's Delta's staffing level? Not even close. Spirit pilots have the opportunity to bank more clams by doing less and enjoying more at home time (ala FedEx style) than most if not ALL.
Comparing only pay rates as a function of job status or superiority is as foolish as letting your 6-year old manage your 401k portfolio.
There are many others, but here is just ONE example in the Spirit agreement: CONFLICTS. This provision alone is worth at least 25% of the listed pay rates, and that's without even turning a wheel!
So before you let the big carrier boys get you down, just remember, they are about to drop a galactic scope relief turd in the bowl. They have bigger problems then just Defending a simple pay rate figure.