How to draw the line between naivety and mercy

Today we went to a shopping street in Vienna. Normally I don't like to go shopping and often prefer online shopping anyway ... As we entered the street two women came towards us and gave us (me, my sister, and mother) roses while saying "all the best" several times.

I thought "hmm .. is it world's women day? or any other special day I do not know about?".
At the same time my sister was thinking "hmm .. is some political camp promoting for the next elections?"
Neither of us were right. After the few moments we were thinking this and that, the woman said "please, make a little donation for the children". I didn't even ask for which children, which organisation, etc. I simply obeyed.

My father thinks that this is naivety, that they used me and I allowed it. I think that I was simply taken by surprise and had not enough time to think. But what if I had time to think about it. Would I be able to say no and give the roses back??

The same thing happened to me as I was in India. At every traffic light when the car stopped , several children came to my side of the car and begged. It is difficult to say a firm "no" in such situations, especially to children. In foreign countries it becomes even more difficult ... they don't understand what you are saying and often do not care anyway ... the people around you look at you to see how you are going to respond, etc.

I think women are being more used in such situations. In India they never asked my brother, but only me, saying "didi didi, khana khana" meaning "sister sister, food food".

In short: it is hard to be a woman in this world, I'd say. :-)