I'd say it boils down to a question of intent. In the case of Boeing, you have a complicated system whose engineering intricacies make it exceedingly difficult

I'd say it boils down to a question of intent. In the case of Boeing, you have a complicated system whose engineering intricacies make it exceedingly difficult for anyone to anticipate all possible failure modes. In the case of VW you have execs trying to make an extra buck off of knowingly pumping an excess of pollution into the atmosphere. The first seems negligent at most, the second seems malicious.