Many traffic lights do have cameras/sensors to detect waiting traffic and measure wait times. It's not always quite so simple as using ML to adjust light timin

Many traffic lights do have cameras/sensors to detect waiting traffic and measure wait times. It's not always quite so simple as using ML to adjust light timing, however. In big cities, at least, traffic lights are sometimes deliberately intended to slow traffic down in order to reduce volumes and speeds on the street, or to reduce congestion elsewhere on connecting roads.