I remember seeing a study (and spent my legally required 5 minutes Googling for it before I gave up), where older people are having collagen formation issues (a very common thing, its one of the major signs of aging), and supplementing collagen was not improving their condition, only adding C, an important cofactor, improved collagen formation rates meaningfully.
I doubt they suddenly stopped eating sources with C in it because they became 65+; instead, I think its more realistic to consider it as the end result of a lifelong habit of low C.
Personally, in my own life, its only as an adult that I have a significant constant source of C. As a child, citrus fruits, non-citrus fruits also high in C, and vegetables known for their high C content weren't common; all of my C came from kid's multivitamins, and who knows if the amount of C in them was sufficient.
Now, I eat sweet potatoes almost every day. Lots if C in those.