I'm not a CFR, but I can definitely see the sense in having beacons to clear the way - much in the same way that doctors do. Correct me if I'm wrong, but doctors are not given any exemption from road rules when using green lights but use them to clear a path ahead of them. Would (does) this not lead to more confusion, though, when other road users see the green lights and believe that the driver is exempt from certain road rules, as drivers under blue lights are, and treat them as though they were?