That's been around since WP 8.0 for the Tap to Pay integration in Wallet that only ever worked with Orange France (as it required secure SIMs and cooperation by the carrier). That switch is still there in WP 8.1, despite the tap-to-pay functionality being pulled from Wallet and put into separate apps (that's what the 'payment apps' part refers to), and this settings page hasn't changed in Windows 10. Hopefully the rumored payment thing pans out though.