Why are most employees judged based on their cvs? why not judge people mostly based on face to face interviews?

A example for your question.

Assume you are in a super market to buy a perfume or deodorant. You won't just go on trying all the brands, instead you will first review the descriptions, select a few of your taste and choice and then finalize the decision with the one you suppose the best.

Same way employers cant test everyone. They read our descriptions and select us on the basis of our description.

Best of luck.