Technology

Look for a square or an X (or a square with an X in it) right Infront of the stop line for the lights. If it's there, that detects a car waiting.

There may be more of them further up the road to detect more cars waiting/arriving.

They are basically using big loops of wire to detect cars through magmatism.

They tend not to detect cyclists, so I often have to move to the side and wave cars forward so lights on side streets will change.

Sensors on a main road and well set timers after a few months of data can do wonders and be extremely low cost, but it requires some upfront spending and enough public will to put up with bad traffic until everything is tuned.

Sensors are cheap and have been around for a long time, but I'm going to guess the number one reason is the small part. Fewer cars = less traffic.

I've actually watched a city I visit regularly grow over about 20 years and it went from them having zero traffic to Los Angeles style traffic jams. This is despite their best efforts like making extra wide roads, using roundabouts, etc.

I would be happy for sensors at traffic lights that detect whether cars are there or not. I don't consider that to be meaningful surveillance.

Of course there has to be a sore loser China bad commenter with some made up BS