[dragonwriter]

> By accepting the app, Apple is implicitly allowing the use case of using the phone as a scale.

This may be a bigger issue than just concern that customers might ruin their screens (and blame Apple.)

Scales (for commercial use) are regulated, and devices marketed as scales but intended for only non-commercial use are explicitly labeled "not for us in trade"; Apple probably doesn't want to be seen as marketing or endorsing the iPhone as a scale, even implicitly.