Carbon frames, Titanium frames and Stainless steel frames are beginning to appear with lifetime warranties. This is unquestionably good and I hope the vendors remain in business long enough to support any claims. However, I can't recall seeing any offers of lengthy warranties on steel framed bicycles and I suspect it is due to the risk of "tin worm"/ oxidation/ red rot/ corrosion.
With about seven steel bicycles in my collection rust is a bit of a concern, especially on my Brompton, Basso Viper and Condor Tempo which I need to/plan to use when the weather turns foul. My main worry is the inside of the tubes so I began looking into spraying Waxoyl inside the frames, after all it was the thing to do for older cars.
Technology has advanced since the 90's and I found the latest recommended rust preventative tested on the very good Road.cc website.
It was a bit pricey but it should hopefully be sufficient to apply to most of my steel framed bikes and if there is any remaining then I've still got a couple of old classic cars which might also benefit.
I just need to find some time to do the jobs.