Said space shuttle firmware engineer probably never had to solve a pop-quiz problem on a whiteboard. It's much more likely that he/she deliberated for weeks about a simple change with the rest of their team, and perhaps even with the person/astronaut they might kill if the change had a bad bug.
Who cares if this person can't solve fizz-buzz on the whiteboard? That's probably not even a relevant skill to the job opening you're filling, or a skill they have ever needed to hone or practice. It's like determining a marathon runner's worth by timing their 100 yard dash.
If I ever need to do another coding interview again, I'm gonna troll the person asking the question by pulling out my phone, googling their question, and consulting the stack overflow post in the search results to solve the problem. And why not, this is how I (and the vast majority of people) will actually get the job done in a real situation.