This statement appears to contain an internal inconsistency.
Isn't the job of a programmer to solve problems? The code is just an expression of the solution. If he/she solves 10x problems in the same amount of time as an average programmer, that programmer has 10x the productivity.
Maybe the key word is "work". The expert does not have to "work" as hard to solve the same problem. With code, the expert will sove a problem with less code. Then again, anybody with experience knows, it is much more difficult to create a small simple solution for a problem.