Sorry that you found the question subpar. We have had a candidate once and I reviewed some of their code on screen share. I remember that the candidate had some confusion and said that Arrays is the same Hash Maps which shows lack of understanding of data structures. We are find highly skilled PHP developers who lack understanding of data structures. Unfortunately the nature of business requires our senior developers to have a good command on the basics of programming apart from knowing a language or a framework. I hope that this would explain why our interviewers might ask very basic questions to highly experiences candidates.

*Re-commenting because of grammatical errors in the last comment* Sorry that you found the question sub-par. We have had a candidate once who I interviewed. We reviewed some of their code on screen share and I remember that the candidate had some confusion and he believed that Arrays are the same Hash Maps which shows lack of understanding of data structures. We are finding highly skilled PHP developers who lack understanding of data structures and algorithms. Unfortunately (or fortunately), the nature of business requires all of our senior developers to have a good command on the basics of programming apart from knowing a language or a framework. I hope that this would explain why our interviewers might ask very basic questions to highly experiences candidates.