Comment by espadrine

I might be wrong, but I read APFL's no-checksum decision as founded upon Apple's hardware-and-software strategy. Given their situation, they can decide that checksumming is a hardware problem. They can build their latest devices with ECC, and require customers to only use Apple-developed USB keys. (I would not be shocked to learn that, in late 2017, Apple starts selling USB-C storage keys preformatted as APFS.)