There are some standards. The ingredients are listed in descending order of size (ie the first is the largest).
They can get around this in a few ways (though this isn’t really relevant here), such as for example preserves having this ingredient list: blueberries, sugar, corn syrup. Even though the amount of blueberries is technically larger than both sugar and corn syrup, sugar and corn syrup (still basically sugar) can add up to much more than the amount of blueberries. By including multiple types of sugar they can sort of hide the fact that the largest ingredient is some form of sugar
It depends how close you sit to your TV and how large the TV is. I can tell a difference if I’m close enough or if the screen is large enough. As well, try turning on a streamed 1080p show and using a 4k bluray (if you have all of thrsr things). When you stand close (like, closer than you’d watch), you can really see the difference. As you back away, it becomes less noticeable, but even at comfortable viewing distances people can see the difference
You can see an example on your phone. Try watching a video in 1080p and then 480p. You should notice a difference, even if you hold your phone a foot from your face it’s the same idea when watching on a tv.