Chances are people just have the screens set to high.
To be honest I would say a very high number of gamers run the gamma WAY too high.
For example. In games like left 4 dead, they do have spots that are supposed to be very dark.
Another thing that may effect you is that every screen is different. some simply do not display dark colors right, they just all become on shade of dark grey.
If it bugs you, you may try to increase the game gamma to see if it helps.
An image showing how some screens just do not display darker colors. the screen on the left is set to 14 for brightness(out of 100) while the screen on the right is set to MAX and it still can not show dark colors at all. the strange blue tint is screen glow.
So this may have to do with the screen more than it being a TV or monitor