There are key differences in the technical performance of the display devices which used in PC and television viewing. Many consumer television displays may do well to resolve 2MHz horizontally whilst the PC user's screen is commonly able to resolve 20MHz. Add to this the effect of interlace and the effect of big screen flicker for the television viewer and it is clear that the displays are not likely to be equal. This greatly affects the amount of information which can be reliably placed on screen at any one time. Presentation on a television screen has been the preserve of the broadcaster.
Television screens display the same picture in the same way on all television screens.
Partly this reflects the very much simpler technology present in television and, in turn this reflects an intrinsically conservative approach to change which viewers have towards the technology they buy. Television receivers are very much bought on the premise that they shall have a long and useful lifetime. The same anticipation is not so of a PC even though the baseline cost to the consumer is similar. Most television displays do not even deliver the full picture to the viewer. This can be contrasted with the PC screen where every addressable pixel will be visible.