Because it takes skilled thoughtful effort to design an interview process that gathers sufficient information, corresponds reasonably to the work required, but

Because it takes skilled thoughtful effort to design an interview process that gathers sufficient information, corresponds reasonably to the work required, but which doesn't require a whole bunch of company-specific context or impose prohibitive costs. The company I work for tries to focus our interview challenges on knowledge that you would actually exercise and think about while on-the-job but isn't language and framework specific. It has trade-offs (we have a take-home test, which does impose a cost on candidates' free time) and I would be interested in seeing someone more experienced than I go through the process and evaluate how well we do.