Indifference... or lack of knowledge. I've conducted hundreds of interviews and it's interesting how many people know their O notation and how they can write code that theoretically is "efficient"... but performance is in the details and in knowing the stack top-to-bottom, and most people just don't know that. And the real problem is that they don't know what they don't know.

You'd say that code reviews is where this stuff should be caught, but unfortunately, code reviews are performative in most cases or the reviewers also don't know / care about these details either.