It's simple: not buying them is the way. There is enough competition to just buy a screen that will not do that.
This is a false dichotomy.
My love of cinema drives me to have certain features in my TV: 4k, OLED, HDR. My hatred of ads drives to me buy certain products to use my with TV: Apple TV.
Apparently I can attempt to import one from Romania, but that seems fairly complicated. Even sites that recommend dumb TVs just recommend SmartTVs that works well as a dumb TV.
My guess is that the vast majority of people will trade data for a cheaper price point every time (my wife is certainly one of these people), so the market just can't support the volume of sales necessary to make the price point of dumb tvs competitive.