I think what you're seeing here isn't recycling so mach as "planned" obsolesence by the radio sales and manufacturing industries. If I understand correctly many new radios were often sold by allowing a generous trade-in amount for the customer's old used radio. The trade-in units, working or not, were usually destroyed as shown in this photo. The idea was that the fewer used radios that were available meant that more new radios would be sold. A great plan for the manufacturers and retailers but maybe not so much for the consumer. The radio business wasn't the only one to take this approach. I think it was a pretty common tactic with jukeboxes, pinball machines and vending equipment. Sun auto test and tune equipment was sold this way into the '70s at least. I'd guess that Allen and other brands of engine analyzers and test equipment were likely treated this way as well. Even back at that time you seldom saw used Sun Testers for sale, and I suppose a lot of them were leased rather than bought outright anyway. Once traded-in or off-lease they'd be scrapped to promote the sales of the new equipment.