Put yourselves in the shoes of an employer. There are a hundred candidates applying to your position. Would the answer of "just trust me" convince you to hire one person above the 99 other applicants? If only one of those 100 applicants showed they had the skills you wanted, right out of the box, wouldn't you feel better about hiring him?
I think the attitude of "they should hire me, since I can learn anything" is self-centered. There are a lot more people that can't learn. Without testing methods available there is no way to distinguish the self-starters from the frauds.