Not everybody is convinced that it's "more productive" to produce more bugs.

Pareto, context and objectives are importort factors in that decision.

Coding a 5 lines bash script in rust brings safety but it's not a win.

If the bash script had an incorrect value due to an implicit conversion, then yes, the rust implementation is clearly a win.

So, context.

Not everybody, but probably enough people. Actually you could even build your career around it. Some guy got into office at night time to fire estinguish the problem his buggy code created. Got appraisal from management for such extra effort. Everybody else's not so buggy code didn't get that appraisal...

Bingo. When performance is the overriding goal, it is often a matter of choosing which deals to do with which devils.

Must be down to all those idle hands he can bring to bear on a given task.