Some people don't share the same opinion as you regarding donations.
EDIT: For example, the reason I said no, I don't agree with $1 being added to every order because if I want to donate then I want to do it myself, in this case I probably would willingly donate a $1. Potential problem: what if I order something, decide I want another, go back and order another and I have to donate another $1 to order it. If you want $1 for something then just increase the price of the product by a $1, but if it's forced don't call it a donation.