There's also a good chance that, at least in part due to Apple's greed and extravagant prices for chargers / fragile power cords, many people are using knockoff chargers and don't know it. See also Amazon happily selling knockoffs as real -- Apple claims 90% of chargers it recently bought on Amazon are fake and is suing the supplier, though unfortunately is not suing Amazon [1], which might help Amazon find the will to stop people selling fakes.

[1] https://9to5mac.com/2016/10/19/amazon-fake-apple-chargers-ca...