Fluid change intervals nowadays are driven by marketing, not by real world conditions or warranties.
People squealed they were getting ripped off by 6000 mile points intervals, 12,000 mile spark plugs etc, that's how electronic ignition came about. That's also why you see the mfgs trumpeting 7500 mile (or even longer) oil change intervals. Sure, the car may last the warranty period if these are never done. Synthetics and better metallurgy contribute to the longer life cars have now but are by no means the final answer. If you don't want to be a slave to GMAC or Ford Motor Credit or whoever for the rest of your life, then how the car lasts after the warranty period becomes of paramount importance.
Me, I don't care what other people do with their cars. Tha's their business and their wallet. (In fact, it's better for my wallet if they DON'T take care of 'em. ) I take care of mine because it's my wallet and I want them to last; the longer I go with a solid running and driving paid for vehicle the better off I am financially.
If I change the oil every ~4500 miles over a 200,000 mile period and it costs me $25 a pop, that's ~$1150.00. How much is an engine?
Transmission: over that same 200,000 miles I change it every 30k, costs me ~$85 each time, that's ~$570.00. How much is an automatic transmission?
Axle fluid, ~$40 to change it in both, ~60k intervals, ~$135.00. How much are two axles, even from a junkyard?
Over 200k miles, this works out to ~$1900.00. Engine = $3500.00, transmission = $3000.00, two boneyard axles = ~$700.00 (roughly). That's ~$7200.00. Or a savings of ~$5300.00. That's not including maybe having to hunt down a replacement vehicle at, say, $10-$15k for something used or greatgawdamightyholyschitt for anything new.
Seems like a pretty damn good deal to me.