legislated nostalgia
n. Nostalgic images or ideas presented in such a way that even people who weren't yet born seem to "remember" that time.
An even weirder ad is the one going around for the clothing chain Old Navy which plays on characters from the ancient American sitcom Green Acres: It shows a modern update of the show's storyline, with the show's theme music.

It's selling carpenter pants, which are themselves a retro item, but not from the same period as the show. Old Navy sells clothing for young people, especially teenagers, who are too young to remember this sitcom. We know the sitcom, of course, even though we may never have seen it, because it is a constant cultural reference. This is an example of what Douglas Coupland once called legislated nostalgia…We think we remember Green Acres from our childhoods because the people who make media images certainly remember it and so we must of necessity share their memories.
—Russell Smith, “TV spots sharpen avant-garde's edge,” The Globe and Mail, November 06, 2002
There was a point, sometime in the last few years, when culture stopped looking forward," Albarn says. "I come from a generation that spends most of its time looking backwards. It's legislated nostalgia — you have to take part, whether you remember it or not.
—David Sprague, “SBK Bets On Blur To Clear Way For Brit Bands In U.S.,” Billboard, December 11, 1993
1991 (earliest)
Legislated Nostalgia: To force a body of people to have memories they do not actually possess.
—Douglas Coupland, Generation X, St. Martins Press, March 15, 1991
As the earliest citation shows, this phrase was coined by the writer Douglas Coupland in his 1991 book Generation X. It seems an unlikely candidate for linguistic longevity. (Unlike, say, Coupland's more famous coinages, including the magnificent veal-fattening pen, which he defined as a "small, cramped office workstation built of fabric-covered disassemblable wall partitions and inhabited by junior staff members." Coupland is often given credit for coining McJob, but the term was in use at least five years before Generation X. Still, it was Coupland who gave the word the more general definition now in use: "A low-pay, low-prestige, low-dignity, low-benefit, no-future job in the service sector.") However, I managed to find over two dozen citations, at least eight of which made no reference to Coupland or his book.