I agree with the statement "they cost money for both parties" but I disagree with "in that sense it's fair."
Individual consultant: loses 5 hours of interview time (and commute time) or take-home exam. Let's call it $800 for the sake of argument.
Company: loses 5 hours of interview time, plus the time it takes to "quiz" the exam.
Individual loses money that he / she uses to pay their mortgage.
Company loses profit because the time spent interviewing the candidate could have been spent working on feature Y of the application. So shareholders / VC's lose.
So you're saying it's fair that the individual contributor who loses half a day's pay in your interview process is equivalent (you DID use the word "fair" so that's an equivalence argument you made) to a company's loss of a few hours out of the many thousands of man-hours they rely upon? It's a .0001% of their profit, assuming the employers don't work a few hours more to make up for the lost time, because they will (they're salaried!)