There is ways to make very bright and effective bicycle lights that put out just as much light as car headlights that do not blind other traffic any more then car headlights do (on dim setting) this requires the same level of application engineering that go into car headlights (granted there are some annoyingly blinding car headlights that seem to lack this as well) unfortunately most commercial bicycle headlights do not take this into consideration. It is possible to build your own that do which is what I have had to resort too doing. My home-brew LED bike headlight assemblies work just like car headlights with "dim" and "bright" settings (actually multiple levels of dim and bright) where the dim setting throws soft non-blinding but fully visible and illuminating light and the "bright" setting throws a powerful blinding beam. Just like cars I have to dim my brights when there is other traffic approaching and sometimes we flash each other back and forth when one of us forgets to dim. All it takes is some common sense and a little electrical, electronic, and optical know-how apparently the companies selling bicycle headlights can't be bothered to do this. Might be just another part of the "But bikes don't belong on the roads especially at night!" cultural taboo. Why design bike headlights built for on road use with other traffic if you don't want bikes on the road with other traffic. Seems to be how it is being played.

Also someone mentioned how flashing bike lights don't allow other drivers to see exactly where you are. This is true as the human eye/brain does need a constant on steady light to "lock onto" and properly judge position, distance, and speed and it is very difficult to do this on a strobe type light. It is also true that a strobe type light does "get noticed" better then a constant on one especially if it is not that bright. My solution is to combine a constant powerful steady on tail light with a smaller less powerful blinky or better yet make the light gently (not annoyingly or harshly or too fast but noticeably) pulse in brightness but still stay constant on like an old magneto powered motorcycle headlight does. This can also be done with LED bike lights and is very effective but implementing it is a pain since there isn't very many off the shelf solutions.