Mil invites us/who pays

My MIL will say things like I didn't get the kids a birthday gift let's go to the museum instead. What it turns into is tons of me planning and then also having to buy the tickets. I stopped buying their tickets for these things. But it isn't a gift for the kids if I'm buying? I find it weird and my kids are super young. If they wanted to just go do something I'll pay for it. If we invite them we always pay for them. Is this weird?

My MIL was telling my mom oh we want to go do things instead of gifts but they don't ever pay for it? It makes it sound to my mom that they are generous and it's far from the truth.

Update: We did said family activity. She shared pictures and shared her involvement with going to the activity. Everyone kept saying how generous her gift was. I verbally let them know it was paid for by myself. I saw lots of shocked faces on not sure how to respond in the conversation. I am not to be petty but I also don't family to be thinking she's generous when she isn't. As she doesn't give gifts and claims she does. I am probably being petty but after having to buy tickets parking and lunch and she left after only an hour I was annoyed. It was a two and half hour round trip for us with three kids on memorial Day so it really takes up my spare time energy and resources when I'm on a tight budget.