[labster]

Pedestrians have a button to press to let the signal know they exist. Until we invent car-hands, that seems equivalent enough.

[rincebrain]

In a number of those systems, the buttons are a placebo that are wired to nothing. [1] [2]

[1] - https://www.nytimes.com/2016/10/28/us/placebo-buttons-elevat...

[2] - https://www.nytimes.com/2004/02/27/nyregion/for-exercise-in-...

[laurieg]

In Japan there is sometimes a button for cyclists/motorcycles to push to get the lughts to change. I assumed this was because there is a sensor in the road to detect cars, but now I'm not so sure.

[CuriousCosmic]

Not strictly true, a number of different traffic systems detect cars using detection methods such as cameras and radar/microwave.