As a check against this, I looked for 42" computer monitors, which don't display ads. There are $600 4k 42" monitors in stock at CDW, for example. The same size 4k SmartTVs are about $300. So, yes... there appears to be about a 50% discount for TVs vs Computer Displays, part of which could be a subsidy, most of which I suspect is volume driving down the cost of production.
Double check the refresh rate, input latency, and color gamut for your comparisons. Computer monitor user concerns are quite different than tv screen users.
TVs also spy on you. That data offsets some of the cost. They also often have lots of other compromises, from chroma subsampling to overscanning, that make them unsuitable as computer monitors.
