Try buying something online with cash.
That’s a straw-man argument.
I guess Amazon won't be including a built-in cash-in receptacle (like the ones they have at self-checkout stations in various stores) in their delivery drones any time soon, will they?
On the other hand, online rules should not always have to apply to in-person rules. (For example, just because people can't really kiss online, does not mean they should also not be able to kiss in person.)