The early 90's also had issues with some foreign sourced steel not having the proper cathodic protection. Those tended to corrode much quicker and more likely to see perforation than surface rusting.
Might also have something to do with better directed underbody shielding and exhaust placement. The components are still the same aluminized coated mild steel that they've used before. Initial exhaust temps are higher - in effort to improve emissions and light off the catalytic converter faster.
Mine is the same way - over 206K miles on my 2002 and all original exhaust - except for the exhaust donuts that were replaced at the 100K mark. Muffler has some surface rust, but not perforated. My 1996 Camry has almost 500K miles, all original exhaust on that as well - but I think those Camry's had a stainless steel exhaust, not 100% sure on that though.
This only applies to OEM - once you go aftermarket, then all bets are off. My experience is that you are looking at replacements every 2-3 years or so - not decades.