Quality of the system is such a massive dependency here, I can well believe that someone watching old reruns from a shitty streaming service that is upscaled to 1080p or 4k by their TV they purchased from the supermarket with coupons collected from their breakfast cereal is going to struggle to tell the difference.
Likewise if you fed the TVs with a high end 4k blu ray player and any blu ray considered reference such as Interstellar, you are still going to struggle to tell the difference, even with a more midrange TV unless the TVs get comically large for the viewing distance so that the 1080p screen starts to look pixelated.
I think very few people would expect their old wired apple earphones they got free with their iphone 4 would expect amazing sound from them, yet people seem to be ignoring the same for cheap TVs. I am not advocating for ultra high end audio/videophile nonsense with systems costing 10s of thousands, just that quite large and noticeable gains are available much lower down the scale.
Depending what you watch and how you watch it, good quality HDR for the right content is an absolute home run for difference between standard 1080p and 4k HDR if your TV can do true black. Shit TVs do HDR shitterly, its just not comparable to a decent TV and source. Its like playing high rez loss less audio on those old apple wired earphones vs. playing low bitrate MP3s.
