I'm not saying that you're not telling the truth, but I am saying that most people who say that they give food actually give nothing (neither money nor food), but tell their friends and random message boards that they give food, because it avoids looking miserly (if you give nothing) or naive (if you give money).
And I agree with you completely - most people that help, do that because they think that helping people is the right thing to do.
I'm saying that there are a whole other (much larger) class of people who actually don't help at all, but say that they do (to their friends, on HN etc) because they don't want to be thought of as miserly.
Just look at the comments on this thread. At the moment, by far the largest number are saying that they don't give money, but that they buy food or other goods instead. If that were true, I would expect to have seen someone give a homeless person food at least once in my life, or offer to take them somewhere they could buy food, or just stop to talk to them. As it is, I've seen zero people give food, maybe a few hundred people give money, and hundreds of thousands do nothing.
When we are at a supermarket we don't usually notice anything beside our own grocery list...