alt Hacker NewsA manufacturer can target multiple markets and make different choices for different markets.
The Samsung S90D (a 65" 4K model) you bought appears to sell for about $1000. Looking at Best Buy's site, you can also buy a Samsung 65" 4K TV for as little as $180 (model DU6900).
Yes, there's other differences. LED vs OLED etc. But at a glance they seem equivalent to a consumer...and one costs 5x more. The $1000 TV is targeting a market that expects more from their purchase and would potentially grate at a persistent sign-in notification. The <$200 TV is targeting a market that wants a big TV and hasn't thought much past that.
There's definitely a chance that on some models Samsung would be more aggressive about enabling smart features, because those models are expected to be subsidized by ads.
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It's like poor people living in the crowded business district with little peace and giant billboards shining in the bedroom window.
There are free TVs now that are completely subsidized by ads: https://www.telly.com/
But don't think people who can afford the more expensive TV are also more tech-savvy. Some just want a nicer TV. Also, they are a much more lucrative target market than people who cannot afford the nicer TV.
While all of that is certainly true, even the DU6900 has the "Start with Smart Hub Home" option that defaults to enabled but can be disabled according to its manual. I assume that's what OP is seeing; it's a common thing to want to disable on Samsung TVs.