It reportedly cost Disney the same amount as installing a "fifth gate" [i.e. an entire new theme park] to rollout FastPass+ across it's Orlando operation. 4 theme parks, 2 waterparks, 30 hotels & Disney Springs all covered. The MagicBand / FastPass+ experience is unique & works seamlessly across the entire resort.
MagicBand will store your theme park tickets, FastPass+'s (bookable 30 or 60 days out online), act as your hotel room key & allow charging to your hotel account across the parks. Could you imagine if Merlin attempted anything similar? It'd be done on a shoestring (probably outsourced too) and would crash faster than The... OK, we won't go there!
MagicBand (or the "hard" tickets - actually plastic cards) all use RFID. We only need to look at Alton Towers previous dabble with RFID technology - outsourced to YourDay. It failed, miserably.