[paxy]

> Also I guess about 70% of (pre-qualified) candidates would outright fail the question

This is probably right. Companies still use these questions, though, because they do a good job failing candidates who are not technical enough for the role.

What you're essentially doing is filtering out bad candidates and selecting from good ones based on luck.

[hikarudo]

In other words, the companies are optmizing for precision, rather than recall, which makes sense.

[ghettoimp]

I've done a lot of interviewing and participated in a lot of hiring decisions at a very large tech company.

I think our process is guided far more by tradition than deliberate optimization for anything in particular. :)