Why can beggars not be choosers?

Every once in a while I notice the following disturbing (at least to me) trend on the streets and subways of NYC: there will be a homeless or near-homeless/poor person asking people for money, food or clothing/other kinds of help…this will be followed by some person responding (in a grand gesture, for all to see) by giving an item of food or something else that the person asked for…in turn, the beggar will thank them but refuse one or all of the items and provide an explanation re: allergies to a kind of food they were offered or that they are looking for warmer clothing or that they don’t eat meat, or whatever…in closing, the person who provided the item will act supremely offended and indignant that this miserable being dared to speak against something they gave of themselves so selflessly.

This always amazes me really because I just don’t get the anger – was it really that difficult for you to offer your cheeseburger and have it returned back? Do you have to scoff and look around for others to validate you like ‘can you believe that homeless asshole said he doesn’t eat meat’? After all, no harm was done, you had your food returned and the person moved on. Can a beggar not have personal beliefs and ideas or physical reasons for not accepting certain things? These incidents just go to show me how giving, for so many, is all about showing off and expecting and unwarranted amount of thankfullness in return. What do you think?