Many people don’t know usb-c cable is universal, and apple only advertises chargeing iphone with macbook and ipad charger.
I imagine most of these people use an iPhone, and they will certainly waste their money on an “Apple cable”.
Plus many of these tech-illiterate people are likely on a lighting iPhone with a barrel jack Windows, they won’t even know they need a new charging cable until they realize their old lighting cables don’t work.
And USB-C cables aren’t universal, I imagine a bunch of the cables you have can’t handle the higher voltage charging Macbooks have. But if your cable is capable of a higher standard, it’ll work fine with anything below it (e.g. I use my Macbook Pro charger to charge my Android phone, keyboard, and mouse all the time).