I can see where they come from using the horizontal louver system behind the lenses, but I'm not sure if I really agree with it tbh. They also tried to market the spider-web lenses with the added bonus of being anti-phantom, when infact, IMO, there is more chance of getting phantom off the lense, because the grroves cut into the lense give the light chance to diffuse and reflect insid the lense before it even reaches the reflector.
I'm supprised the Sira lense technology hasn't spread to other countries, however it could be out DfT being a greedy bunch and wanting to keep hold of the general design themselves.