The trouble is that 25lx at street level is often accompanied by vast amounts of light going upwards and outwards. This means that 10km away in the national landscape there is a gigantic light dome filling about half the sky and at least as bright as a local floodlight.
Indeed and this guidance specifically condones this. I can perhaps understand why levels of lighting might vary between zones but cannot understand why they consider higher percentages of upward flux acceptable in more light polluted areas. Table 7 for example makes no sense. Why should 35% upward flux be considered acceptable for amenity lighting in zone E4. I see no reason why the fraction of light emitted upward should not be controlled to the same extent everywhere.