I had an 1869 Colt in kit form in the 70s that was sold as a stainless steel pistol. It made up into a pretty pistol. Shine like a ruby in a goats a_ _.
There were also the 1851 (490 produced-$$$$) and 1861 (6 produced-$$$$$) 2nd Gen Stainless Steel Colts.
Uberti made 5 different models in SS in the early '80s; but they're harder to find than the Colt's. USFA also made a few, but they're $$$$$ if you can find one.
The why not now is probably related to poor sales when they did make them.
Fingers (Who wishes Uberti would start making SS Colts again) McGee