Comment by pishpash

Conversion is different at $1100 vs. $400 so it's not a straight 1:1 $167 vs $70; the beancounters will weight by the likelihood of getting the amount in the first place. You also have to consider the long-term value of converting, e.g. the being in the Apple ecosystem vs. going to Android if they don't convert. Finally, the cannibalization argument is stronger if the alternative is a new low-tier phone like SE or some special pricing for third-world markets. That's not selling at $1100, it'll be much closer to residual on the used phone. It's hard for me to believe the market pricing is off by so much that something that destroys value in the system like shredding working phones is a net economic gain even for Apple.

Note that in your earlier link they are shredding non-working phones that need repair, so those residual values are closer to scrap value. That's different.