I collect for the charity Action for Children.
We are instructed to be polite to everyone, and always say thank you to those who put money in our collecting tins.
We never ask for personal details, and as far as I know, (but I may be mistaken) if you are asked for them it is illegal, and you are not in the wrong to refuse this information.
You do not have to give to any charity, this is entirely up to the individual, whether they give or not.
However, I do feel that your article does give genuine, polite, non-judgemental collectors a bad press.