I have not had any experience with Magic Bands, the closest I came was on my last Disney trip and they had just rolled out the NFC room cards for charging. My experience at that stage of the project was awful, I needed a pin, I needed my pass (for a discount), I needed my ID (to prove it was my pass), AND I still needed to sign for the charges....but on the way I quoted you.
I do not think Disney needed to re-invent the wheel here, the could have went with card readers from the typical payment processors, instead, it seemed like they went in house and built a system that would only read Magic Bands, they then needed to interact with their internal systems...I imagine there could have been a work flow that used commercial card readers (so that could use NFC from a Magic Band or a cell phone or an NFC enabled card)...anyway, they could have kept the payments via the cards and the Disney customer account separate....I think they just wanted to process like they do at the hotels where they wait until you check out or until you reach your charge limit before the run all your charges at one time (I assume they get a better rate with one big charge as opposed to many small charges)...no clue if they save enough in processing fees to justify an internal system that only works with internal systems.
I guess it is in detail like that where I see there were aspects for the Magic Band project that should have been pieced out to a company that already had a lot of the technology...I mean Iger is on the Board at Apple, yet I never heard talk of them using beacons (as a way to push targeted adds) and such...just seems like they wanted to do everything themselves...