Zero failure rates not just 0.000…1 are a very different and unrealistic bar. Software must be treated as actively malicious from a hardware standpoint from multiple bit flip errors etc. So it comes down to designing hardware capable of the task that’s also incapable of causing harm even with hardware defects etc.
Meanwhile it must also be strong enough to move and restrain a range of infants which is a level of force capable of harm without any possibility to fail deadly.
You might always get hit by a freak accident. Or an unlucky combination of cosmic rays replaces all your software (including all the redundant and fail safe systems) all at once.
This is all extremely unlikely, but not literally 0.
Note: I specifically mention an unlucky combination of cosmic rays. You can protect against a single or even a handful of cosmic rays just fine.
For this device you agree with mine and the original posters position.
A Diaper however can be designed not to risk grievous bodily harm for an infant when used correctly by a human. If someone doesn’t change their kids dipper that’s neglect by the parents not a negative news story for the manufacturers. We’re a long way from this point when it comes to robots.
Meanwhile it must also be strong enough to move and restrain a range of infants which is a level of force capable of harm without any possibility to fail deadly.