[didntcheck]

If you mean the ones that are just a painted strip on the ground, then OK, but for existing traffic lights controlled ones it doesn't seem unreasonable at all. Sensors to detect pedestrian and/or car presence are already extremely common. E.g. all modern [1] pedestrian crossings in the UK have similar sensors, which can extend the crossing time if it detects someone still in the road. And of course your local drive thru can detect your car pulling up, though usually by induction coil

[1] https://en.wikipedia.org/wiki/Puffin_crossing - standard since 2016