I agree that the friend should be paying her own way. However, I am a bit confused by the OP's comments that she just assumes that BFF will attend all of these events. Does the BFF feel obligated to attend? Will the OP be OK if BFF declines to attend any event that isn't free? If the OP expects that BFF attend these events then OP should pay. If OP doesn't care and won't hold it against the BFF if she doesn't go, then the OP should tell BFF that she doesn't expect her to attend and therefore won't be paying.
BFF genuinely loves coming to DD's events, even ones I had assumed were too "small" for her to attend. Like little classroom plays, if BFF is able to get off work. BFF has attended every (free) winter and spring concert, every (free) ceremony, even though most of the time, DD has no special role, no solo, and is not graduating. BFF also attends the (free) school break camp shows. BFF just loves the girl and doesn't want to miss out.
That said, BFF's presence has become important to DD, so attendance is not 100% nonobligatory...but since BFF says she to want to go on Saturday night too, that's a clear indication that this is not a hassle, it's a pleasure to see DD on stage. Hell, maybe BFF is looking forward to the awkward carnage of an elementary school play.
There's no question of suggesting that we won't invite her to future paid events. That could be a friendship breaker. I really love my BFF; we have been friends for 20 years and do an awful lot for each other. I think she's got some deep-seated resentments about the lopsided family life of a single person with no children.
I'm going to go against the grain a bit. Picking up with what you say here and thinking about the other thread about reciprocation of gifts - does your BFF give gifts to your child? Does she take her out for a trip to the park or the zoo? Does she ever babysit? I'm not meaning to attack you, OP , I think your response to which I'm replying makes sense and you are doing the right thing. But, here's the perspective from a single woman who has an awesome neice. I buy her birthday and Christmas gifts, send her postcards when I travel, I buy plane tickets to visit and I take her out for special outings when I'm there. I spend alot of time and money on her and I am happy to do it. It is an investment in an important relationship
and I'll continue doing it no matter what. The reciprocation is the love and relationship
and worth every penny, but that doesn't mean that after awhile I'm not going to think a little bit about it. When I do visit my sister's family, my sister often will give me cash to pay the entry to the zoo or for the parking. We're both financially comfortable and it isn't a big deal for either of us to pay. But I think it is very thoughtful of her to pick up a few of those expenses and I think she does it to kind of offer a form of reciprocation.
Now, I would never state that I expect my sister and her husband to pay for anything for me, in relation to their daughter. But I appreciate it when they do. I wish the BFF in the OP wouldn't loudly proclaim her philosophy about this - I think that is offputting. But I can understand the mindset of the single, child-free adult - in order to develop and maintain the relationships
with children who are important to us, it does mean that we give generously of our time and money, and it's nice for the parent to acknowledge that now and then in a material way.