It might be in their courses, but they doesn't mean they understood or retained it properly. Lots of programmers get by without ever reimplementing those in industry work
In fact implementing them for production should be a fire-able offense if they have not searched for a library that does it.
The only place in industry where this should be used is in interviews and candidates should never be asked to do it again if they pass that phase. We cannot have people working on stuff they interviewed with.
