Just curious, has anybody else noticed that some airlines require that "all window shades be up for takeoff and landing" while others do not? Even regional affiliates for the same carrier often differ. CO mainline, CO Express, DL mainline, WN mainline, FL do not require window shades to be up. ASA (DL rj operator) and Comair (also DL rj operator) do require window shades be up. Whats the story here? Its not really that big of a deal to me, but I just wondered why the other airlines require this.

Btw, I searched this forum but was not able to find any previous posts about the subject.