How do hiring committees for research positions view getting "scooped"?

I'm a little surprised by the implicit assumption that "scooped" ==> "no paper whatsoever."

It's often possible--and desirable--to publish the scooped work anyway. It might have less impact than it otherwise would have, but it's miles better than nothing. Furthermore, it's unlikely that both papers tackle the problem exactly the same way; highlight those differences in your revised version. If nothing else, replications are increasingly appreciated. This is especially true in trendy areas, where both scooping and dubious, non-replicable results are most likely.

It would be gauche for you to complain about this directly on your cover letter or CV (how would this even work?!). With a publication, however, your references can write:

"Grad Student's main project, characterizing the properties of l-Phlebotinum and d-Phlebotinum, was just accepted at the Journal of Decent Results. Although his thesis committee praised the work as a technical tour de force, it unfortunately attracted less attention than it might have after Evil et al. (2018) published similar results last December in Science."

Obviously, you'd prefer not to get scooped, but this does demonstrate that you're working on 'hot' problems that people do find interesting, which is better than nothing.

They might empathize if you somehow decide to mention it somewhere in your CV/cover letter/research statement/whatever. But in the end, you will be judged based on what you have actually produced. "Getting scooped" is difficult to verify if you have no publications. It's easy to say "I was totally going to say that!" when someone else says something clever. It's another thing to do the research well, write it down, iron out the inevitable kinks, fight with editors and peer reviewers to get your research publish... and to do all that faster than your competitors. Unless you can prove that you have great potential, then it is likely that committee will prefer someone who has published papers over someone who has almost published papers.

I am afraid that "I've been scooped" during the job interview in academia will be perceived as an upscale version of "a dog ate my coursework" excuse, particularly if a candidate has no publications at all.

• Academic jobs usually require PhD, and PhD students are usually expected to publish a few papers during their PhD. At a very least one would expect papers based on PhD thesis.
• Scooping is possible if the candidate presented their result publicly but was too slow to publish it. In academia "publish or perish" is an important motto, particularly for early and mid-career academics. A proven inability to publish results in time is not something hiring committees will particularly like.