Doesn't have to be a law. Can just be standard engineering practice.

Websockets for example are always encrypted (not e2e). That means anyone who implements a chess game over websockets gets encryption at no extra effort.

We just need e2e to be just as easy. For example maybe imagine a new type of unicode which is encrypted. Your application just deals with 'unicode' strings and the OS handles encryption and decryption for you, including if you send those strings over the network to others.