This issue with full beams is a right bug bear of mine! I mean surely with full beams a driver can see from here to the moon yet only ever spot me within 30 metres or so, or not at all!
And am not exactly invisible as anyone on a Frrttc ride will know, I have three flashing front backups on my helmet, one half watt'er on constant and on Cateye on flashing and pretty much full reflectives, yet they still persist!
I find wiggling the handle bar left and right so the main beam flashing in and out of their vision helps, if not my fist, from once sheilding my eyes, turning into the obligatory w*****r wave! And then I grin!