Isn't it a reasonable hypothesis that your union has much to say about what you get paid? There is a pool of money for salaries that gets divided up.

Hypothetical pay scale here.

FO
Year1 = 24/hr
Year2 = 28/hr
Year3 = 33/hr

Capt
Year4 = 60/hr
Year5 = 67/hr
Year6 = 75/hr

Would the pilots agree to the following flatter scale?

FO
Year1 = 34/hr
Year2 = 38/hr
Year3 = 43/hr

Capt
Year4 = 50/hr
Year5 = 57/hr
Year6 = 65/hr

Discuss.