Indeed, if they can't see a RR coming, but you'd be surprised at the sheer amount of tools who will pull into your path. If you have the DRL's on, I find they tend to hesitate more because they can't judge your speed quite as well with the lights being so bright.
There was a test done many years ago, perhaps on Tomorrow's World or some such where they had a tank on a hill and you could see the outline perfectly. Then, the same tank, the went round it's basic outline with light bulbs and lit them. They were about as bright as side lights, the tank disappeared, blended into the background due to the ambient light. I can't remember the term for it, but I always remembered that sidelights in daylight are about as much good as a fart in a jar.
Anyway, the reason for the DRL's in my case was I paid 55 quid for the LED headlamp bulbs and I like driving with lights on so thought "ooh, that's gonna burn them out quicker...!" Hence 10 quid for the DRL's. And they come on soon as I fire the engine as I wired them to one of the engine relays.
Besides, George blends into nothing on a bright sunny day as she's sky blue, so better to get noticed