One factor was union rules at the time that prevented the BBC from re-airing shows more than a handful of times. The fear of the actors' unions was that once the BBC and ITV had enough of a library of recorded shows they would reduce new productions (and thus new jobs for actors). In retrospect, it looks silly because no major network is going to fill its schedule with reruns (at least not in prime time) but in the early years of TV, particularly the early years of video recording, it was a not unreasonable concern. So, this meant that aside from foreign sales, an old video recording of a show would be unairable and thus of no use to the BBC, so why use up valuable shelf space to keep it, particularly when video was expensive and money could be saved by taping over old videos with new programs? Video transferred to film would be usable for foreign sales but after a few years, and particularly after conversion to colour, old black and white film stock of old TV shows would also be useless. No one imagined there'd be such a thing as a home video market, let alone streaming, or that there'd be an interest in old TV shows more than a decade after broadcast.

One of the most notable losses of old television was the almost complete erasure of Johnny Carson's first decade hosting the Tonight Show in New York, before moving to Burbank. People blame NBC for lacking the forsight to keep the tapes but apparently, what actually happened was Carson kept the cassettes and shipped them to Burbank where they took up several rooms of storage space in NBC''s Burbank studios. The property manager of the building worked for NBC, not Carson, and when more space was needed in the building for offices, he made room by having the tapes taken out and dumped, without clearing it with Carson's staff. Sometime later, Carson asked Fred DeCordova to pull out a specific clip from an old show that he wanted to reuse and DeCordova was horrified to discover that the tapes had been dumped and had to tell a furious Carson who had the manager fired.