> Can't you rule a lot of those candidate (other than CV liars) out algorithmically?

I think all companies do this, but it's really easy to game the metrics. People do it unconsciously, even.

> This seems especially difficult when hiring graduates/junior roles due to the lack of unknowns.

Yep, so it takes hours of interviewing per candidate, across dozens of candidates just to hire to minimise the risk for one role. At a global level, FAANGs are hiring loads, but at a team/local level there's never enough people due to specific team needs or turnover.