There's one other advantage to wireless here: a bionic prosthetic is moving a lot, and that's not great for wire harnesses or connectors. Going wireless potentially allows for greater range of movement (or at least removes the engineering challenge of making it durable long term).
They both nominally have ~~5~~ 7, but I'm guessing there's at least one person choking on a fish or chicken bone at any given time to slightly skew the average.
Where do they come from, fedi-bot Joe?