If you are morally obligated to use your own resources if you have them, then you're stratifying society. The financially comfortable can never ride a bus. The rich cannot drive themselves. Nobody can ever learn what those less fortunate are like, and must necessarily look down upon them and use their imagination to figure out what "those people" care about and need.

So that's not a great outcome either.

(I don't exactly disagree with you either. Accepting a scarce resource from someone when you possess significantly more? That rubs me the wrong way too. Get their mailing address and pay it back later, in spades, if it deprived them of something!)