There is pretty much no way to measure that objectively in practice. For example, our time spent on reading computer science books, learning more math, talking

There is pretty much no way to measure that objectively in practice. For example, our time spent on reading computer science books, learning more math, talking with other good programmers all affect our programming productivity. Moreover, learning to write clearly in English (or one's native language) also impacts how well one can code and comment. But much of those 'practices' has accumulated over years or even decades, some since childhood, some from family influence without one's trying. The system you propose, if implemented, will soon degenerate to how well one can pretend to be disadvantaged or fake the effort, so that more rewards will be offered even when the work output stays the same. This is equivalent to giving bonus for the hours spent as face time in office while chatting on Facebook there.