In Never Let Me Go, why don't the "donors" in the story just escape? Why don't they just refuse to sacrifice themselves by giving away their organs?

The clones
don't think of escaping for the simple reason that this is not really a novel about clones or
bioethics. The point is that we just do. All of us. Most of us are not even aware that of the
inevitability of our fate. We just go on though we know that there is only one end. To read the
novel as sci fi is to misread. The entire premise is a symbolic one.