Why are we tolerating this criminal behavior by corporations?

Because it's done in the open and it's accepted as part of the cost of the device. This is an expected consequence of our adtech surveillance economy where devices are now subsidized because they can harvest data about you, your usage and your behavior to sell on an ongoing basis. We've been screaming about these sorts of practices since the late 90s and consumers have just blithered right along with every new and creepy intrusion because they get cheap things and don't think about the real costs or consequences. And so ... Here we are.

Unfortunately, that's no guarantee. I believe some devices have been found to scan for any open WiFi and join silently so they can phone home.

Another alternative is don’t connect your TV to the internet.

https://www.sceptre.com/TV/4K-UHD-TV-category1category73.html

This brand sells all non-smart TVs at non-commecial prices.

If it is a Samsung tv, they have been automatically connecting to any open wifi, maybe your neighbor has one. And there goes the data.

Avoid Samsung.

You'll have to desolder the WiFi card inside. Check teardowns of TVs from now when deciding to buy a new one

A doubleplusgood book.

Ah (Or)well

I'm just waiting for them to add a sideband channel to some LoRa network so they can exfiltrate data even when their devices are "offline"

It's a bit difficult, you'll need be good with your solder.

Just give it the wrong wifi password.

If you block ALL traffic from it? Sure. It's possible but more involved and requires the right hardware to block their tracking domains while leaving streaming apps working.

It's best not to use smart TVs as well smart TVs. The apps they have are almost always slower or inferior in some way to the versions you get on streaming devices, updated less often, etc. I recommend pairing a TV with a quality streaming device like an Nvidia shield (or shield pro) or an AppleTV*. Alternatively if you want something a little cheaper in Androidtv space there is the Walmart brand Onn 4k pro.

*warning with Apple is while they're pretty good on privacy (meh, there are no excellent choices that support streaming apps in 1080p quality) and don't have ads their app-store is a bit more locked down. They have all the major streaming services but if you do high seas type stuff it will be more involved and difficult. Though if you have a local media collection (source your own discs or high seas) and run Plex or Jellyfin they have apps for both of those that work great as well as Infuse which usually requires a subscription unless you don't need 4k or any proprietary audio codecs like dolby for any of your media. I personally can say I enjoy my AppleTV 4K and I think it's a great device but I run my own media-server and have some common streaming services I pay for.

No. You need to request your Netflix video, you need to ACK the segments of it you receive and a lot more.
At the very least you'll need to maintain a detailed whitelist of allowed domains and especially for the manufacturer some packets might he OK, like checking for updates, while others you'll wanna block.

It's likely a lot easier to just get a dumb screen and have the smart in a device you control.