The key word in the definition of exploit is "full" use. To simply use something and derive a profit from it is not necessarily exploitative, as the noted comment suggests.
In the context of this thread, the original claim put forth is that being "used" for 80 hours is in fact exploitative; by one calculation, this amounts to 100% of your waking time in a standard 5 day work week, assuming a typical 8 hour daily sleep period. On the other hand, being used for a 40 hour work week is not exploitative; you still have 50% of your time remaining for non-work life. The math here is used for illustrative purposes, but a reasonable interpretation of "full" would tend towards 100%, not 50%.
Workers are truly exploited in some cases. To label a 40 hour work week as exploitation, in most cases, is simply hyperbole that diminishes the real suffering and ethical issues of actual worker exploitation.
The usual counterargument is that the worker agreed to exchange their labor for a price so it's "fair" and therefore not exploitation, which is obviously juvenile. I appreciate that you at least go beyond that simplistic platitude, but it seems equally shortsighted if not ridiculous to get caught up about what qualifies as "full use" of a human being, which is probably why most people just stop before going there. You didn't even mention the wage! I have to ask: would a slave that never works beyond 40 hours/week be considered exploited?
In the context of this thread, the original claim put forth is that being "used" for 80 hours is in fact exploitative; by one calculation, this amounts to 100% of your waking time in a standard 5 day work week, assuming a typical 8 hour daily sleep period. On the other hand, being used for a 40 hour work week is not exploitative; you still have 50% of your time remaining for non-work life. The math here is used for illustrative purposes, but a reasonable interpretation of "full" would tend towards 100%, not 50%.
Workers are truly exploited in some cases. To label a 40 hour work week as exploitation, in most cases, is simply hyperbole that diminishes the real suffering and ethical issues of actual worker exploitation.