He recounts of an issue with a customer complaining about low Internet speeds, despite being located close to the distribution building for the whole area. Seemingly, everything should've been fine. A cable leaves the distribution building, goes into the ground, and reappears a short distance later near the customer's house. Upon close inspection it was discovered that the cable did not take a straight route underground - instead of cutting the cable to necessary length, someone just buried the entire spool, and the total cable length was close to a kilometer or so. The signal, unboosted, barely got through to the other end.
So sounds like a movie plot
Just lends itself to the story possibly being an urban legend.
His guess was that (a) nobody bothered looking in the box and (b) they were just testing voice quality, which was fine, but the actual DSL signal was showing lots of dropouts.