If you get paid for donating blood or plasma, is it earned income or what? I mean you are selling your blood, not really donating it if you're getting paid. Or is it like hobby income?
This is legit and it's a real need and it's a pain in the butt (I mean the jokes write themselves!) so it makes sense to pay people for their trouble. It's weird that you can't sell a kidney but you can sell your poop. But you're going to poop regardless and just literally flush it down the toilet, so if you have ideal gut bacteria and can help people with a fecal transplant and get paid for your trouble, you can make a living doing this for a few minutes a day. Weird planet we live on.
The catch is that over 99% of people will not qualify. But no harm in trying and if you do qualify you just won the poop lottery.