Color photos are made up of up to three or four layers. The primary colors and a base.
Because of this, the colors are in the layers, not imbedded into the paper. If they are kept in the least amount of UV light, they will fade.
The Black and White stuff is embedded into the fiber of the paper. It is still reactive to UV light, but it is more about the paper than the print itself. Crappy paper = crapy prints.
The other thing about black and white is that they were generally processed by hand. The chemicals were handled with a lot more care.
A fiber based black and white photo was washed thoroughly, getting all of the chemicals out of the paper. Otherwise it would turn brown pretty quickly.
Color prints of “snapshots” would have gone through automated printers. The process was quick and cheap. And you got a quick and cheap result.
Finally, the new archival prints made from digital photos are done with better inks and they are embedded into the paper—as the black and white silver was. That is way current prints, done on high end ink jets, will last about 500 years without significant fading.
Excellent comments to go with my post #52. Few people really understand just how major of a role quality paper and processing method lays. It ain`t just the processing chemicals.
As I recall, Kodachrome was different, in that it was developed more like black and white film, and the color dyes were added during processing. This is why Kodachrome could not be developed by home processors, and it’s also why properly stored Kodachromes (save for the first couple of years from the 1930s, where the dyes have decomposed and the images have become mostly black-and-white) have held their colors well for decades.