Depends on the type of work you do and what the company pays you for. It is the means (your time)? Or the outcome?
Had quite a few clients and employers asking and haggling over trying to get it both ways.
If you consider a creative job where you only care about the output, then the more creative it is, the less (above an undetermined threshold) time spent working and output are correlated.
The means (again, time spent) not being an accurate predictor of the outcome, they don’t matter much, and there is no reason to tie the salary to them.
If you consider a non-creative (factory / fruits picking) or vaguely creative (low-level factory-style coding, data input) job, then the less creative it is, the more time spent working and output are correlated (up to a physical / mental exhaustion threshold).
Here, the means are a good predictor of the outcome, hence the salary being tied to the number of hours spent working.
It really depends ¯\_(ツ)_/¯