È una fotocamera a luce rossa

No, it checks mobile phone usage

Not sure if it’s used in this case for this purpose. But I’ve seen these used in certain areas to check traffic on lights. Which can change the behavior or durations of red/green lights to avoid long queues in certain turns or lanes.
You usually can tell it’s used for that when they also have a small red led on them which turns on or off indicating when the camera goes on or of as it periodically checks how many cars are there.