There is a universally accepted standard. And I believe the usual suspects have each had it implemented on their manufactured "smartphones". Each device can pu

There is a universally accepted standard. And I believe the usual suspects have each had it implemented on their manufactured "smartphones". Each device can put its network interface into AP mode. I think the marketing term is "WiFi Direct". But good luck getting Apple and Samsung devices to both discover and associate with each other. If it feels like you're continually being corralled into sharing files with the person next to you via a third party's servers and an open, insecure, untrusted network ("the internet"), then maybe you are. It is not necessary to use the internet and third parties to do something as simple as transfer files to the person sitting next to you (without using removable media), but it's easy for companies to convince users that this is the only way to do it. And in most cases no convincing is even necessary because users fail to consider the alternatives.