An essential element of psychological safety is a blameless culture.
In the real world it is impossible to know with certainty what will happen when we do something until we have done it. There is no such thing as zero risk and therefore making failure “unacceptable” is completely unreasonable. In fact it is stupid. When failure is punished then we lose all value from the failure – it becomes a cost not an asset. Worse still, we ensure that in future people will avoid doing anything.
Because we are not psychic, failure is inevitable even with our best efforts. In fact, failure is a normal part of work, and is the path to success, if we learn from it instead of burying it.
We should embrace failure even incompetent failure. If somebody does something stupid, we should think them for exposing the weakness in our system that allows somebody to do something stupid.
A punitive culture is destructive to agility and creativity.
When we foster a culture of embracing failure, then people are prepared to attempt innovation, and are willing to work in high-risk environments.