You're not actually initiating a transfer of money. Sure, it feels like that but in reality they're just storing your CC info and debiting you either in advance (like gas) or settling up (like hotels). You have to have a prior relationship with the company handling your account and figure out a secondary out-of-band payment flow. The fob doesn't really add anything except as a holder of your account id.
The only thing they have in common is the physical action of "boop boop" at a terminal or scanner.
It's more like a contactless gift card: since you can't use your change for purchasing something different, the payment is in the purchase of the gift card.
The only thing they have in common is the physical action of "boop boop" at a terminal or scanner.