I'm not sure if this is a question of principle or policy. Let's start with the question of principle. Certainly, volunteer organ donors deserve moral kudos, but should they get to move ahead of others in line to receive organ transplants? That really depends on what the principles should be guiding the distribution of this scarce resourse. Should it be responding to the most urgent medical need? Maximizing life expectancy? Maximizing contribution to social happiness? Something else? If, say, it was giving priority to most urgent medical needs, then I don't see why preference should be given to volunteer donors. Perhaps the thought is that the benefits of a practice should go disproportionately to those who contribute to the practice, for, according to this principle, volunteer donors contribute more to the practice of organ doantion and transplant and so deserve priority. Perhaps being a volunteer donor could serve as a tie-breaker among transplant candidates who were otherwise equally well qualified (along whatever other dimesnions are relevant). But I find it hard to believe that the practice of orgna donation and practice should distribute benefits according primarily to contributions. It seems more like a charitable scheme meant to respond to need than an insurance scheme. A different consideration is that of creating an incentive to potential donors to agree to volunteer their organs after death. But there are many ways to incentivize conduct. Rarely, do we need the incentive to be the same kind of good as the very good we are trying to promote. But these claims about principle are complicated and contestable and don't yet address directly matters of policy design.
Read another response by David Brink
Do you think that volunteer organ donors should get preferential treatment over non-organ donors in regards to receiving organs?