Answer:
Francois and Perrault value Buck for his strength and eventually come to hold him in high esteem because of his amazing ability to lead the team and do their work for them. They lack any significant personal attachment to him, however, as they see all their dogs as tools that they must take care of in order to do the work they've chosen. They know to take care of them and feed them and rest them when needed.
When Buck falls into the clutches of Hal and Charles, they have no idea of how to take care of the dogs and expect them to have limitless strength. They drive the dogs until they can no longer stand. This exposure to human stupidity and pride perhaps starts Buck down the path of learning what to do and what not to do.
Step-by-step explanation: