Society is responsible for each and every member of it. Having 0.001% of population's lives ruined because of an error is not acceptable.
Humans may be slower and less efficient than machines (and require living wages), but humans are flexible and understand context. Replacing them with machines will only remove the useful human capabilities that we need so much in this society where most of the rules are still ad-hoc and implicit.
Imagine being assaulted by a robot policeman whose crime detection facility has malfunctioned, while you can't even complain to his robot colleague because it hasn't been programmed for malfunction of other robot policemen.