The position of blinds for takeoff and landing is a matter, in the first instance, for government regulators and in the second instance, for the carriers. The different procedures on BA and EK are simply due to the fact that they are regulated by different governments and are different businesses.

No different than other bits and pieces such as use of electronics, use of glassware on the ground and luggage size.

As to "sleeper service" it's really a change of culture. Sleeper is not just about the meal in the lounge or dimming the lights, it is about keeping the back-and-forth in the cabin to a minimum. Everytime a FA walks by and interacts with a pax, that disturbs others.

On a sleeper flight, not only should the lights be dimmed and the cabin announcements be kept to a minimum, but service should be accomplished quickly, e.g. single tray and lengthy discussions kept to a minimum. That contravenes the service culture of the premium cabins on most cultures.