The larger problem is the cult of "Big O" and its use as a form of signalling in interviews. If I wanted to test whether a candidate understood Big O, I'd ask

The larger problem is the cult of "Big O" and its use as a form of signalling in interviews. If I wanted to test whether a candidate understood Big O, I'd ask them if there was a difference between O(1) and O(0). What these companies want is to see if the candidate understands program performance in general. Big O is the vogue (in my view misguided) way to do that.