Actually, the assumption that paying people will result in more blood is perhaps more problematic. The research seems to indicate that people actually like to donate. Although, work is ongoing.

http://freakonomics.com/2013/06/05/is-paying-for-blood-a-goo...

Quote:

    The position and guidelines of the World Health Organization (WHO) and several national blood collection agencies for nearly 40 years have been based on the view that offering economic incentives to blood donors is detrimental to the quantity and safety of the blood supply. The guidelines suggest that blood should be obtained from unpaid volunteers only. 

    However, whether economic incentives positively or negatively affect blood donations (and other prosocial activities) has remained the subject of debate since the positions were established.

    Evidence consistent with the WHO position came originally from uncontrolled studies using nonrandom samples and, subsequently, from surveys and laboratory studies indicating that economic incentives can “crowd out” (decrease) intrinsic motivations to donate and can attract “worse” donors.

That's a different thing than is being suggested though, I believe. That study sounds like something along the lines of a "Come donate and get $50" type of arrangement. The parent's suggestion was more along the lines of specifically targeting individuals that have e.g. O blood or rare properties in their blood, removing the likelihood of quality going down.

It's an interesting ethics issue.

I'm sure there are people out there who would be more than happy to have their "job" be providing blood or other things like it. And I think it would probably benefit society as a whole for something like it.

But it does seem like it could very VERY easily go south really fast. And there are a lot of ethical issues with it (like a salaried-donator wouldn't be able to do anything to risk the health of that blood at any time, and would it be okay for someone to permanently change their body to better accommodate something like that? What about temporarily change their body?)

> would it be okay for someone to permanently change their body to better accommodate something like that?

Many professionals in other fields already permanently change their bodies to better suit their profession. I don't see why a full-time Blood Donator would be any different.

That's an interesting hypothetical, but there's no way someone could donate blood "full time" to earn a living wage. There's an upper bound to how fast one can produce blood, and a high proportion of people are capable of doing it, so each person can represent at most a miniscule proportion of total supply. It would be like making a career out of football if almost everyone were equally fit and talented and lots of people played all the time for fun and there were no NFL.

But what if we could we increase the amount of blood someone can donate. I know something roughly similar is done when donating marrow.

What if we could augment humans to be able to produce absurd amounts of blood and make it so it was a full-time job for those people?

If we could increase the amount of blood someone could donate by 100x, would it start to become cheaper to just hire full-time donors rather than deal with all the expenses around donations? And would it be ethical even if the donors we're fully consenting and paid a good salary?

Like you said, its a interesting hypothetical to say the least!

You’d have to find such a person first. From the article, there were a unique set of circumstances that doctors don’t even truly understand that led to his blood having these properties.

That was then. He may have unusually high levels, I'm not sure, but donors are induced to produce the antibodies these days (they volunteer and it takes a while to build up production and so on).