I agree with some others who say if she is paying her own way, she goes to the new place. Throw some small snacks in the handbag.
As for her no quite picking up on what you are trying to teach her about the value of being a good neighbor to those less fortunate, don't feel like your failing. Right now she is a teenager and it soundls like maybe some of her actions are being dictated by wanting to be like her friends and have things like her friends. That doesn't mean she isn't learning. Someday hopefully it will click and she will realize the valuble lesson you are teaching.
My boys didn't understand why their dad and I would take vaction time to work at the local Christmas program where we gave away gifts and food to those in our community who don't have as much. One year they asked to join us, and then they got it. Especially when they saw the parents of a few of their friends come through. They are both generous young men now who are stuggling themselves in this econemy but still spare a little for someone else.
Good luck on your delimma.