Comment by calinet6

I'll try to address a few points here:

-What's the core problem?

Evaluation. In this case, evaluating intrinsic difficulty of a certain task or group of tasks. There's no way to do so systematically, without inside knowledge about the task. Foe example, suppose you want to rank two mathematicians without a clue about the subject matter. One presents short proofs to many problems, while the other presents enormous proofs with great effort. There's no way to tell if the problems are really difficult or not and chose the reward without having knowledgeable peers evaluate the a) hardness, and b) usefulness intrinsic to the problem. In fact, it could be argued that simplicity is a good sign, but it's impossible to tell whether the problem is unimportant/trivial to begin with.

- Why do people think in this way, instead of more systematically?

Without insider knowledge, which management sometimes lacks, you cannot confidently rank as stated above. But there's one trivial thing you can do, which works, but not necessarily efficiently: if the solution works/is found, reward the solver, otherwise punish/look for others (and reward them more). Hard problems skillfully solved will go unrewarded and good performers will gravitate towards fixing crisis instead of doing good ground up engineering as they should. That's the aspect of inefficient, but it is possible with enough money to manage this way.