There is no such thing as zero risk. This is because no physical item has zero failure rate, no human being makes zero errors, and no piece of software design can foresee every operational possibility.
Nevertheless public perception of risk, particularly in the aftermath of a major incident, often calls for the zero risk ideal. However, in general, most people understand that this is not practicable, as can be seen from everyday risk of death from various causes. Therefore the concept of defining and accepting a tolerable risk for any particular activity prevails.