I think the reason why first two examples can say that they are safe is that in case of failure, people die. And thus there was a regulation introduced. People

I think the reason why first two examples can say that they are safe is that in case of failure, people die. And thus there was a regulation introduced. People generally care when they can die. In case of software, rather rarely people die and when software is being done on something human critical (a friend of mine works on pacemakers), there a great deal of care being done. So basically it's a wide range from DIY using a cheap wrench to person rotating a torque calibrated wrench on a rocket. Because just like the hammer, there is a wide range of use cases, some critical (e.g. pacemaker), some mundane (e.g. ecommerce). Planes and elevators always have a risk of crashing and killing humans. And it did. Software doesn't.