If you think it works - where is the photo sensor?

Lights work on either timing (ugh) or based on a combination of heirarchy and traffic based on pre-set timers and sensor information. You can clearly tell where the sensors are - you'll see rectangular cuts and boxes on the road. The sensors work by detecting a change in inductance in the area above the sensor.

Motorcycles usually have a hard time "tripping" the sensor and often break the law because they're left with no choice lol.