No, it's not the same as you not replacing your old car, since you don't drive your car 10-12 hours per day, 365 days per year like AA does with its airplanes. A typical AA MD-80 burns about 3.5 million gallons of fuel per year and at current prices that's nearly $8 million per year per MD-80. If you could make the car payments on a new car with the money you'd save on gas by buying a new fuel efficient car, then you'd replace your old car with the new car. But you only drive your car a part of the day and not 10-12 hours each day. Your relatively small gasoline bill (as a percentage of the price of a new car) is why gassing up the old car instead of making large new car payments makes economic sense for you. Not so with AA and its MD-80s, which fly at least 10 hours per day on average.
The fuel savings by flying a new 738 instead of an MD-80 more than makes the payments on the new 738. That makes the purchase of a new 738 a cash-positive activity. It gets even better when you factor in the maintenance savings (parts and labor) on a brand-new airplane that's still under warranty. When oil again climbs above $100/bbl or $140/bbl (as it surely will), the decision to buy the 738s will look even more impressive.
As an aside, AA isn't paying anywhere near $80 million for each new 738 as you allege; its actual purchase price is less than half that amount. Boeing's list prices are its wish list, not a statement of what large airlines like AA pay when they order 80+ copies to be delivered in three years.
As I've posted before, AA's line maintenance employees deserve to be paid similarly to those at UPS, FedEX and WN. Problem is, AA will never pay the overhaul base mechanics in Tulsa anywhere near those wages. Not when their current wages are higher than at the MROs and allow the Tulsa employees to live high on the hog. Increase their pay to $45/hr or $47/hr or more? Not gonna happen. Figure out how to unhitch yourselves from those boat anchors and perhaps the line maintenance employees might see $45/hr or more.
I agree with you except that I don't consider the OH guys boat anchors, I think their market rate isn't $47 an hr. They are competeing against AAR, TIMCO and others in the US, I don't know how many MRO outfits in other countries, where labor is cheap. I do think that the OH mechs and line mechs should have separate contracts. Funny how when we say that the OH guys say "we should stick together", but before it was "if you don't like it move to Tulsa".
Don't forget when AA gets a new 737, they retire an old S80.