This is probably something you should ask the person who's desperate enough to need that $20, than to decide for them from your point of reference.
If you guys are so concerned about it then create something that puts cash in my pocket. I'll gladly run whatever app you want on my phone if you pay me.
Edit: and now they shut it down. You can thank us privacy advocates later.
it's provably affordable to give everyone the average rent of the world which covers housing (rent of buildings), food (rent of farmland), energy (rent of space used for solar panels, windmills, ...), natural resources (rent of mines).
Resulting in thousands of deaths due to organ shortages, and sex workers being abused by pimps and corrupt cops.
That illustrates fairly well why having an underclass who provides healthy organs to the rich is a utterly barbaric idea.
I don't have a strong opinion either way, but my understanding is that it's very very far from proven that legalizing prostitution improves the lot of sex workers -- I am led to believe that trafficking becomes _more_ of a problem in localities where sex work is legal.
Further, and again no strong personal opinion on the matter, but I suspect you'd see a huge rise in coerced organ selling if it became legalized.
These are questions societies need to answer for themselves, and my central point was that there's already precedent for societies deciding that they don't benefit when some things are available for sale, even if an individual in the moment says they want to sell it.