You mean it's least effort. Least risk would probably be hiring a private investigator to dig up everything about the candidate for the past 10 years.
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.
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.
For a medical doctor it suffices to gets one doctorate. I don't think hospitals will drill him on the core fundamentals of his craft similar to whiteboarding in cs. A patient arrives with a slight fever and a headache. Quick! Which lab tests would you assign him!
When is the last time a hiring manager had 200 good resumes for 3 positions?????
For most companies it is the opposite experience - many open positions, few good resumes, which makes me wonder why they work so hard on keeping people out
Most managers would reach for the algorithms/hackerrank/leetcode because it's the least risk to them.