In the case of Southwest, the difference is around 87 seats.
Paid on a per seat basis, ExpressJet pays better than Continental when comparing 737-900 rates against EMB-145 rates at 10 year captain.
Continental - 173 seats on the 737-900, pay is $167 per hour, and the company pays you $0.96 per seat per hour that you operate.
ExpressJet - 50 seats on the EMB-145, pay us $80 per hour, and the company pays you $1.60 per seat per hour that you operate.
If Continental had that rate for 173 seats, so 173 * $1.60, then the hourly rate would be $276.80 per hour.
The problem is the number of seats, not the pay rate itself. If we're paid by the number of seats, then ExpressJet is paid MORE PER SEAT than Continental.
We need to lose this attitude of thinking a 50 seat jet should pay the same amount as a 173 seat jet. If we want more money, then the airplane needs to make more number, and it needs more seats.