so tv everywhere only works if the channel itself has a login on their website that uses your tv login right? that explains why i can't get nickelodeon/nick@nite anywhere even though it's a channel on the tv source i'm using. because the website itself doesn't do tv login.
You can learn more about it here
Not just a web site that authenticates with the TV Everywhere scheme. For Channels to make use of the network, they must also have a live linear stream of their programming—not just video-on-demand programs/movies—and the stream cannot be encumbered with DRM.
The first reason is why Nick Jr. is available, but Nickelodeon is not. The second reason is why Game Show Network and Bally Sports RSNs are not available.