It’s least risk in the same sense as “Nobody ever got fired for buying IBM [/Microsoft/Oracle].”

In other words, there is actually substantial long-term risk involved in simply electing for the default solution, but it feels safe on the short term and won’t make you look bad to your boss.

That carries the significant risk of getting chewed out for being completely ridiculous.

Is it? It solves the problem of somebody lying on their resume. It's probably not that much more expensive than chewing through a dozen candidates over the course of a year without finding a single suitable match.

I think that's because HR tends toward avoiding false positives rather than false negatives, as the latter tends to be more expensive. Therefore, they would rather miss an ideal candidate in order to avoid the risk of hiring a sub-standard one.

In a perfect world, HR would understand the position well enough to properly vet it but in practice they tend to revert to easier measures like the ones described.

No, they do it because most don’t know how to interview. So, they just do what everyone else is doing.