A allegedly neuro-typical child alleged child turning 14 in November in 7th grade and wanting a new 2015 Mac in 2018? I am beginning to think I need to believe in Santa to make sense of the OP's posts. Or the OP is not sharing that her daughter does indeed have special needs, which is her right, but would change the whole conversation.
The OP did share that her DD has some processing delays in post #6:
DD is an enigma. In some areas, she is very bright and in other areas, she struggles with a language processing delay that spills over into other areas. She has incredible logic in some moments and can be oblivious in others. She spends hours watching you tube vides involving technology (smart phones, ipads etc) and can explain how to fix things but then moments later demonstrated such little understanding about something like did she just meet the real Ariel.
She is in 7th grade. Do some seventh graders still believe?
If DD watches a lot of YouTube vids about computers & technology, it's quite possible DD watched a vid involving 2015 Mac and what it can do and THAT is the one she wants.
Technology, electronics and fixing things are mostly linear, analytical, "left brain," logical thinking. So she may linearly think, if she gets a 2015 Mac, she can do the same exact things. Not realizing that a 2018 Mac may be able to do the same things
and more.
Make believe, imagination, creativity, figuring out if Ariel is real or not , or if Santa is real or not, is a creative, "right brain" process. It's not linear, logical. It takes leaping in imagination & thinking. It's not linear. Thinking is more 3-D. And that kind of thinking may confuse the heck out of Linear/Left Brain people.
So DD may very well wonder: If she meets an Ariel dressed up like Ariel, looks like the Ariel in the Disney film, why ISN'T that Ariel real? In linear logic, it would make sense that she is. If "A", then "B" follows. Possibly the same for Santa. That's why it takes kids to get to a certain age and reasoning ability to catch the inconsistencies and impossibilities and realize he's not real.