Maybe, because you try to hire programmers (engineers at best, craftsmen in typical situation), but you interview (future) computer scientists?

Computer Science is about, you know, science. Not craft or engineering. Typical programmer's work is craft.

You will not hire metallurgist, who trained to develop new sorts of steels, to work in machinist shop.

Yes, big corporations could have research departments, where computer scientists are needed, every big player has one. Most of programmers work is not.

It is problem in our craft: requirement for university degree for simplest positions. It is wrong. You try to hire people who are overqualified in one areas (which is not needed for this positions anyway!) and underqualified in needed skills. Because they were trained for OTHER work!