Question

In Bava Metzia (91b), the Mishnah states that by Torah law a laborer has the right to eat while he is engaged in the actual work itself (and the Torah did not give him the right to eat when moving from one task to another). Then the Sages came and expanded the laborer’s right, enacting that he may eat even when he is not engaged in the work itself (between one task and another), so that when the actual work resumes he will no longer be hungry and will be able to concentrate better on the work, and thus the employer will profit. 
 
This is one example among many in which it seems to me as though the Sages evaluated and understood reality better than the Holy One, blessed be He. After all, if this enactment really benefits the employer more, and everyone is happy because the laborer eats and the employer gets better-quality work, then why didn’t the Torah establish it that way from the outset? In their enactment, the Sages are basically saying: “Listen, Torah, you made a slight mistake, and something better for everyone needs to be fixed.” 
This requires explanation. (Here this is an enactment, not a decree or a fence, where of course there is no question, because the Sages were more stringent, and one can always be more stringent; that does not mean that the original source that was not stringent was mistaken. But here this is a new enactment that seems more reasonable than the original enactment.)