... I don't get the point of this. Is there some cultural US thing related to credit cards that make them a viable strategy or am I just being stupid?
In the US, credit cards convey many legal and financial protections not available otherwise, including built-in car insurance for rental cars, the ability to contest any payment and thereby receive a refund, and no liability for fraudulent purchases. As someone who pays the bill on time, using my no-fee rewards card for the last several years has also netted me more than $500 in free money.
Some nations give such protections to all their citizens regardless of payment form.
Here's an article from Get Rich Slowly which discusses the benefits of credit card use in more detail.
Luke posted about this on SIAI blog. Essentially, you can get a credit card with cash-back rewards program that automatically donates money to Singularity Institute.
This seems to me like a dream come true. Am I missing something? Are there any catches? Is there a better rewards program, which I can use to save more money, so I can donate more money to SIAI?