Polite and respectful, yes, but they also need to learn the meaning of money. If he understands he has to work to earn money, surely that's good? And it's a bit patronising to imply elderly people are always daft, humourless and selfish. They may even have been pleased to see a lad doing something good.
I would be interested to see what they report back to micmak about it. A lot of "my" elderly people would have found that enterprising and amusing and one of my 96-yr-old clients would have said to the boy, "send me an invoice!"