Why it is unethical, nobody is forced to donate

You may be upset by this answer, but I have to ask, Who is donating? Who needs to sell plasma? Who parts with their body tissue for money?

Is it the prosperous? Is it the CEO?

I love science fiction. We've both read or seen the plot where the poor become resources for the rich. The poor volunteer to sell an eye, or sell their organs on death, or sell a kidney. What's wrong with it?

I think if everybody was required to give plasma, with or without pay, then that's fine. I think this is maybe another instance where the well-off benefit from the poor.

Is that ethical? Is that fair. I don't like it. I don't think it's right.

I also don't think it's right that in my country the military is largely made up of the lower classes, because of financial incentives. These incentives might be outright pay, or they might come in the form of college tuition. When we go to war, we do it on the backs of the lower classes. That bothers me.

When considering the ethics of the issue, rather than the safety of the supply, I think paid plasma donation becomes complicated.

And, by the way, I appreciate the comment. I love the feedback.
Rarely do I think "I'm right". I believe I'm right, but I need to listen to others, to have my views challenged.