[DiogenesLamp]

Perfect example of how little these people understand economics and finance. What are the odds that the cost to “send” a “free” sticker is not greater than a $1 donation?

It's a psychological tactic. The point is to get them mentally committed to the idea of donating by getting them to agree to a small amount.

Once someone has mentally accepted the idea that they should donate, as they are getting prepared to send the money they realize that $1.00 is simply silly, and will therefore donate whatever they think is necessary (in their own mind) to keep someone from thinking bad about them.

I'll wager that most of these $1.00 inducements actually result in a $10.00-$50.00 result.

[MarMema]

It's a psychological tactic. The point is to get them mentally committed to the idea of donating by getting them to agree to a small amount.

Yep. I recall it from social psych. It's cognitive dissonance.