Pay for hours worked was an invention of the early industrial era of piecework. Time studies could determine any pieceworker's exact hourly output because inputs, rules, conditions and precise product requirements could be predicted and controlled. No amount of output per hour different from what was mandated was possible. The history of work from the industrial to information era is the history of work becoming increasingly and radically different in character. As controllable work gets automated, the work left is work that has little to do with piecework. In this world, the time anything takes depends on any number of uncontrollable and unpredictable variables. How much time people spend at work does not guarantee any measure of output or value, especially when the work involves any form of creativity, adaptation or people interaction.
What becomes relevant is agreed upon pay for agreed upon constellation of outcomes assessed by agreed upon success criteria. So much for the relevance of managers wasting attention on whether their people are 10 minutes "early" or "late."