Have you worked with any great, experienced engineers who would have had no idea how to traverse a tree?
Years of experience is definitely not a guarantee of competence.
Candidate A: Can recite algos and remembers that Levenshtein distance is the answer.
Candidate B: Has no idea what Levenshtein distance is, writes a brute-force solution with the understanding that it's not an optimal solution. After the interview she spends more time learning what she doesn't know, learns about Levenshtein distance, and sends you an optimal solution via email.
The above is a real-life scenario, so my question to you is - how do you decide who to hire?