Here's a funny story about the FP+ system. I've got a college fraternity brother, very smart, talented programmer type, went to work for a very well-known tech consulting company, moved up the ladder very fast. After a couple of years, he got real quiet about his work and started telling people he had signed a bunch of NDAs and couldn't talk about what he was doing. We all assumed it was government related, but it dragged on for years. Probably 3 or 4 years at least. He was miserable. Whenever we could get him to talk he muttered about antiquated systems and horrible integration and impossible ideas. Finally one day in early fall 2013 he was done. Never seen the guy so happy. A few months later the NDAs ended and he could finally talk about what he was working on, if not give a whole lot of details. You guessed it, he was a lead outside manager for the FP+ creation and installation and what later became
MDE.
Still claims it was the most miserable project he's ever worked on, and he does a lot of government work. Apparently Disney wanted all kinds of legacy systems to work with the FP+, and my friend's firm kept telling them it would be cheaper, faster, and easier, just to rebuild all the systems they wanted connected and leave open ways to connect future systems. Disney never would agree, whether that's because they didn't believe the contractors or just didn't want to, so the whole infrastructure surrounding FP+, Magic Bands, and MDE, and how it all interacts with payment systems, reservations, pretty much everything, is all band aids and tape bridging disparate systems, programming languages, and vendors.
Whenever someone wonders why Disney doesn't do something with a Magic Band that seems simple and makes perfect sense, like adding AP discounts to mobile ordering, it's probably because none of this stuff was designed to work together and everything needs a custom bridge built to support it.