I fell foul of the daylight running thing too with my newish car. I was driving along in the dark, could see perfectly well, but was being flashed insistently from behind. I had no idea what was going on! I fiddled about with the lights so must have switched them on as the flashing stopped, but I was bemused. DLRs aren't pointless specks of light, they were more than enough for me to see on the road I was on.
Anyway, got home, did some googling and realised that daylight running lights only work in the front, so if you leave them on by accident it looks like you have no lights on at the back. Now my lights are on the automatic setting and come on at the front and back. The difference is, my gearbox lights up! And nobody has flashed me from behind since.
The flashing that happens when someone goes over bumps in the road is very different to proper flashing.
And surely people don't flash people because they feel they are going too slowly in the dark when they are the lead car? It's much easier to follow someone! And every time the OP puts her beam on? Seems somewhat unlikely. I don't drive very fast in the dark and have never been flashed except for the DLR issue.
As for telling someone to get their full beam off, if I am the lead car, I will decide if I need it on or not. What is annoying is when I decide I don't need it, and the car behind me decides that it does, even though it's following me! You do not need your full beam if you are behind someone.