Re: This is, of course, not illegal.
I just bought a new smart TV (not because it was smart, but because it was a good deal, even for a basic TV), and I read the screens and screens of terms and agreements that came up for each part of using the TV (even getting it connect to the Internet so that it could get the enhanced epg had about 12 screens of user agreement).
And it was at pains to point out that all of the terms were GDPR compliant, and if it was found any clause wasn't. it would not invalidate the whole agreement, just the affected clause.
And it was wanting to track the use of the telly, the channels that were being watched (for the purposes of starting up at the same point it was turned off - all for YOUR benefit, of course), and any smart applications used, web sites visited, online videos watched etc.
This is endemic. We will now never stop this happening, even with GDPR (which just means that they have to tell you what they want the info for, and ensure that they don't do anything else). They will just publish a wide variety of reasons, in as fuzzy way as they can get away with, and even bury that 10's of pages down a user agreement they know people won't read. Thus they will be GDPR compliant, and still process your data ("you didn't read the agreement, and yet accepted it! It's not our fault, then")
And we will have to agree, or loose access to the streaming and online services that have already supplanted physical media for entertainment. They will ensure that some bit of service you really, really want is contained in an agreement that includes all the bits you don't.
I'm probably going to leave the TV off the network, but I'm sure that I'll not be able to use many of the basic features of the EPG and catchup services without the network being present.