The thing is hash-tables and B+trees are data structures and not algorithms. I agree that if you don't know basic differences of algorithms you will run into performance issues but you will also run into problems if you don't know the difference between a data structure and an algorithm.
Data structure is "a particular way of storing and organizing data", so I think there's not so big distinction between two. More of that, when we think of data structures, we think of insertion/deletion/searching complexity, also we think about space needed (which is also a result of organizing algorithm). So I don't think that someone can run into troubles because of that difference.
