It seems like companies do this because the stakes are so high to them. That is, if you hire this person and they fail, they will somehow do serious damage to the company. If you do this at a large enough scale, then you are putting the company in serious danger.
How do you de-risk this? My take would be to focus on getting "good enough" candidates in and then if they don't work out, be able to fire them easily. It's tough to normalize that. It's legal in states that have at-will employment but it seems that there are still taboos to doing that.
Every US state is at-will. The only state that significantly varies from this is Montana, wherein employment is at-will for only the first six months of employment, which would cover your case here.
I think the taboos are less around the law and more around trying to avoid a reputation that the company will can you a couple months after you've perhaps uprooted your life and moved to a whole new city. I wonder if the taboo will lessen in remote work contexts, where the employee is not so expected to uproot their lives for a job.
Things like this are why I'm glad I live in a country with sensible employment laws.
Firing people willy-nilly SHOULD be taboo, if you find yourself firing people all the time then you're the problem not the people you're firing. Make an effort to support and develop people rather than looking for mythical unicorn candidates.
How do you de-risk this? My take would be to focus on getting "good enough" candidates in and then if they don't work out, be able to fire them easily. It's tough to normalize that. It's legal in states that have at-will employment but it seems that there are still taboos to doing that.