Well, that's true, but it's a strobe light flashing in a complex, pre-programmed pattern that, AFAIK, is different for every city. At some sensor activated lights, it probably does turn the light green. The problem is that one cannot simulate a strobe light with their high beams. The light sensor is also mounted up high, so it can detect the strobes from a distance. Once the car is waiting at the red light, it is too close and low to the ground to be seen by the light sensor. If it did work, flashing the high beams would activate white flashing warning lights that are usually mounted atop the traffic lights. You would notice this.
In the city of Minneapolis, almost all of the traffic lights are on a 70 second timed cycle, and they?re all synchronized to facilitate efficient traffic flow, especially on one ways. There are very few sensor lights. All the emergency vehicle strobes do around here is activate the flashing white warning light. They do not turn the light green, yet some stupid fools sit there and flash away. Low and behold, with a 70 second timed cycle, after a maximum of 45-50 seconds, and all that flashing, the light turns green. Ironically, not flashing my high beams works just as well for me.