Freelancing is a partnership. Much more so than so many other client - provider relationships (getting your oil changed for example.) In many cases, a bad client can put a serious hurt on my earnings and I could put a serious hurt on the client as well. There is a lot of trust there, and each party needs to be highly professional. This isn't a lemonade stand.
If someone approaches me asking me to do something for far lower than my normal rate, then their ability to be a good partner takes a serious hit from my view. It's not about the money, it's the fact that they could make the offer comes off as them being clueless. Not good for a partnership.
At 20 / hour they would be lucky to find someone from a developing nation who barely speaks English.I would direct them to Elance.