While you're absolutely correct, it's worth noting that for most of the disciplines you mention, the actual work takes place on paper too. A mathematician, phy

While you're absolutely correct, it's worth noting that for most of the disciplines you mention, the actual work takes place on paper too. A mathematician, physicist or engineer will spend most of his working life scribbling on paper, so it makes a lot of sense to interview that way. There are plenty of other fields that don't work quite that way. You wouldn't interview a baseball player by asking him to describe hitting a curve ball on paper, or a nurse by asking him to draw stiches on a piece of paper. Every field has its own medium of expression. For many fields, that's paper. For programming, it's a text editor.