I think the difference is that most other things have a point other than having a human being in the scene. So if we're building an airport, a crane collapses, and workers die, we mourn and move on. (And hopefully find out what went wrong so that we don't repeat the same mistake.) And the final constructed airport has its uses, so in a morbid way, their deaths were not in vain.
On the other hand, there's no other point in human space exploration: almost anything a human being can do, a robotic probe can do far cheaper. So the point is literally to have a human being there, and having the human die there is not just a risk, it negates the entire premise of the project.
No one will plan an Olympic opening ceremony with a non-negligible chance of someone dying on stage. Why? Because the entire purpose of the Olympic is to show off your country, and if someone dies while half of the world is watching, you have failed your project. Same thing.
On the other hand, there's no other point in human space exploration: almost anything a human being can do, a robotic probe can do far cheaper. So the point is literally to have a human being there, and having the human die there is not just a risk, it negates the entire premise of the project.
No one will plan an Olympic opening ceremony with a non-negligible chance of someone dying on stage. Why? Because the entire purpose of the Olympic is to show off your country, and if someone dies while half of the world is watching, you have failed your project. Same thing.