Just don't connect them to the internet, now you have a TV that's cheaper than it should be because they expect to show you ads, but they can't
When that day comes buy a monitor, or hack the firmware.
You can always break off the aerial.
How do these things work? Do they have a contract with a phone service operator in each country in the world for unlimited data, or what?
Also the other side is that these cheap TVs are slow as hell. My Vizio has a 15 second startup time before it responds to commands, while it's "Smart"Cast stuff does what it does. This is before it responds to other commands, ex volume. And this is at each session, not cold boot only.