It sounds like you simply don't have experience interviewing engineers, especially since you don't cite any such experience to back up your beliefs. I interviewed exactly 151 engineers over the last year for a mix of entry-level and senior roles, using the same format for all the interviews. The interview is a mix of scenario-based questions and actual coding. There is no discussion of data structures or algorithms, the coding exercise requires no special knowledge and can be done in any language, and there are no trick questions. If you can build useable software you can ace the interview.

My experience lines up exactly with what the GP said. The overwhelming majority of experienced engineers that are interviewing simply can't write useable code. I understand it's hard to believe, but it is the reality whether you believe it or not.