Michael Sandel, author of What Money Can't Buy, argues pretty eloquently the economic and social cost-benefit to pricing things like a placement in line, or a spare room in a house.
To extend one of his examples, Airbnb gives you a hard-cash price for your extra room—or even your couch. One of your friends wants to couch surf for a week.
By past social convention, you'd give it to him for free. He saves money he'd spend on something else.
By Airbnb convention, you charge him for it. You kind of have to, because everyone else is, and you can't leave money on the table. You have cash now, but a bit less than he would have, because Airbnb takes a cut.
Sandel was interested in investigating this society where the rich get the best of everything first, explicitly at the expense of the poor.
So I hope there are some comments investigating whether or not we're better off socially, not necessarily economically, by renting our "excess capacity" or being generous with our "excess capacity."
While I agree that perhaps in a better world everyone should simply share resources unencumbered by profit motive, the assignment of a usage fee to a couch or something does help prevent overuse of resources.
In the case of a friend sleeping on my couch, there is our personal relationship and desire not to cause future trouble that helps limit the possible risk of the couch getting destroyed--having a pecuniary barrier to entry for a stranger to use my couch seems reasonable.
Just because it is not rational does not make it any less real. You don't negotiate with a hurricane. If you are weighing the pros and cons about renting stuff out to a friend, then there are some deeper issues involved. Is this particular friend widely known for mooching off of you? (Why is such a person your friend anyways?) Generally, if you fear abuse of your assets and personal space/time, then you also have some Jungian shadows related to abusing your friendships.
Renting something out to strangers and taking money to mitigate risk -- that seems fair to me. (But risk is emotionally related to the same kinds of issues related to renting or not renting out to a friend, or a friend abusing or not abusing your generosity).
There are ways to deal with the underlying non-rationalizable emotions that does not involve money. Hopefully, those methods will become more popular going forward.
It's interesting. I have never considered this before. Conducting transactions like this means stripping away the impersonal nature of corporations (http://onthespiral.com/unifying-value-universe), makes you much more aware of human nature, maybe gets people to start dealing with it.
Consider also http://playspent.org ... It turns out: a social net is very advantageous. (http://www.amazon.com/Dont-Need-Rise-Network-ebook/dp/B009K8...)
Learning about waste != creating waste, any more than learning about employee theft is responsible for draining the company's resources.
Btw, you're being generous (or not) in both cases; the only question is just to whom you're being generous: the friend, or the strangers ready to put significant money down for the scarce resource.
This kind of economy is here to stay, and it will probably become the norm in many other sectors too. It will be interesting to see the long term effects in the general economy.
By past social convention, you'd give it to him for free.
He saves money he'd spend on something else.