I think we should differentiate between the interview process of Google and such, and (for lack of a better word) average companies. Average companies almost never need sophisticated algorithms and perhaps, even if someone put such sophistication in, the return would be marginal ("sub-linear"). However, this does not seem true for Google and such - the return on investment of a sophisticated algorithm looks to be super-linear. So it makes sense for Google to filter candidates by knowledge of algorithms (among other sophistications) and for most other companies to not copy Google's interview process.