Deep Thoughts at Starbucks

Yesterday, I went to Starbucks to get some work done on my dissertation while my car was getting its oil changed. I went in and a boy, maybe 18 years old, who had some kind of mental handicap was in the front of the line trying to buy a drink. He was difficult to understand, but was showing the cashier his one dollar to see what drink he could buy with it. This was Starbucks and so it's no surprise that there was nothing for that price. As the cashier was explaining this to him, a woman who was waiting for her coffee to be made came over, handed the cashier a Starbucks card, and told her to get him whatever he wanted. He ordered his venti iced pumpkin latte and waited for it while the man in front of me and I ordered our coffees. It did occur to me to offer to pay for his coffee. This is a boy who couldn't buy what he wanted and, while I am by no means rich, I was paying $3 for an overpriced, but small, drink so I could afford another one. I didn't offer, however, and let someone else be the generous person in this situation for a couple reasons. First, I didn't want to spend any more money than I had to (the cheapskate defense). Second, I don't see the benefit of giving coffee to someone. It reminds me of a lady I used to work with who would whine about being broke, but went to a nail salon faithfully every week to get her nails done. Or the Christmas present charities where the Christmas list requests of the needy families includes XBox games. Or the woman who uses the food stamp money to buy food and supplies for the family, and uses cash to buy a large dog and all the accessories that go with that dog. Does the pleasure of a moment of indulgence do something for someone that taking care of practical needs does not? This boy was clearly troubled, as time went on it was clear he was a regular to this shop and he talked to the manager about "troubles" in his last visit not happening again and showed scars from a recent suicide attempt (debatable if it was real as the scar was on his upper arm).
What does it really mean to help someone out? This is something I'm pondering for my dissertation, but on a personal level as well. If I go out and work to aid needy people, do I bring with me all the practical supplies they need only, or do I throw in some toys and candy as well? I just don't know.