I am not a senior level engineer but I recently had an interview where I used an inbuilt collection library for the programming task and the interviewer asked me to write it without the library. That was shocking for me, On the job the expectation is that I use standard tools and libraries to solve the problem but writing a counter, linked list or binary tree from scratch by myself with one person looking over my shoulder is very stressful.

I understand why FAANG companies do so, they need some criteria for elimination but the company I interviewed for was a startup. Sad part was that I was rejected based on this interview.