Suppose employee E makes an error. Management decides to fire them or not. Firing someone for one error (of an accidental, non-malicious variety) makes no sense whatsoever.

The set of companies who do fire for a single accidental error is vanishingly small and very likely the least desirable of employers (as they’re likely making other colossally bad decisions as well).

If you’re working for a sane employer, at-will’s overlay with blameless transparency is fine. If you’re working for a terrible employer, you want to change that anyway.

A sane employer could decide to act on a repeated, long-established pattern of errors, which is frankly good for the organization and the remaining employees. In that case, the transparency around “most everyone’s error rate is a couple per year, while Pat’s error rate is 4 per week for the last 3 months; it’s time to part ways with Pat” is helpful.