[fl0wenol]

These exist in many different generations (sensor-based traffic control devices) but as there are state and/or local certifications each solution and implementation must meet to be deployed, plus the additional cost of installing and periodically calibrating sensors, they are not warranted unless the situation calls for it. The inconvenience of waiting an extra minute at a minor cross-street doesn't usually cut it.

If you live where there is a light that causes disruption or accidents because it needs sensors based on the traffic flows nearby, you should bring it to the attention of your local government. At the very least you could get them to do a study on it.