Other professions get tested. (Score 1)

Where do you get the idea that other professions don't get tested? Perhaps some are more difficult to test on the spot (unlike IT), but lawyers (after passing the bar!) have to submit writing samples (memos, briefs, motions, etc.); potential professors often have to teach an example class to an evaluation committee consisting of professors from that department; doctors take board exams and are often quizzed on how they would approach a certain situation.

Get over yourself and do what the interviewer wants. You should be grateful that they do their job properly and care about the company enough to hire competent IT staff.