Or perhaps they could have a trade-in option where I can bring in an older iPhone charger and they will exchange it for a newer USB-C version. Even if they limited that to a single trade per iPhone purchase it seems like it would be better for the environment than just forcing us to buy a new one, since so few people have the newer USB-C 20W chargers already.

Actually, even from reading the summary I assumed it was a coding error. Isn't that exactly the point, though? If this kind of trivial error gets through testing so easily, how can we have any confidence that more significant and impactful errors aren't slipping through?