When I hired a plumber for my heating firm, I put her through a hazing interview, tested her knowledge of Maxwell relations and thermodynamic equations. Oh wait, no I didn't. As she has been a plumber for years, so we recognised her skill and experience and cut to the chase. When I hired a programmer for our doomed to die VC life support funded fart of a project, we put her through numerous rounds of comp sci bingo a…
My point being, it depends on the role, and the expectations you have for the future of a candidate in your company. Are you hiring a guy to bugfix or implement a couple of features on your web app? Or a guy to design and implement from scratch a app that should have some hope of scaling in the future? Or a guy that can tackle a tricky performance problem you're having?
I'm not claiming the current status quo is alright, but hiring the right people is hard. Knowing CS basics and generalities of the field doesn't hurt either...