https://techcrunch.com/2018/06/04/apple-tv-gets-a-zero-sign-on-mode-for-tv-providers-apps/

Apple TV is adding a new feature that will make it easier for users to sign on to their “TV Everywhere” applications – you know, the ones that require you authenticate with your cable or satellite TV provider in order to watch the channel’s content. Called “Zero Sign On,” the feature is an extension to the previously introduced Single Sign On option. SSO allows users to enter their cable provider TV credentials one time, then be automatically sign into all supported apps. Zero Sign On, on the other hand, doesn’t require you enter any info at all – instead, all that’s required is that you’re connected to the provider’s Wi-Fi network in your home.

The feature is not broadly available right now, unfortunately.