It's kinda funny that so many people have this attitude, when, as a salaried employee, we likely have all done more than a standard 40-hour work week on occasion (or habitually), without extra compensation.

Do you also consider time spent prepping for an interview (brushing up on algorithms, learning about the company, researching interview questions, whatever) as "doing free work"?

I just really don't get this attitude. It's not "work", it's a evaluation. And it's an evaluation that actually displays skills relevant to the job, unlike many other approaches.