[dalben]

The concern was related to being able to know where emergency vehicles were. If you build a system that announces to traffic light “I’m police/fire/EMS, coming through”, you also build an early warning system for criminals and terrorists who either want to avoid or target you.

[mosselman]

That doesn't make any sense. How would criminals know even if the traffic light receives a signal like that?

[ralferoo]

I think these systems used RF before, so anything in the vicinity could listen in. That said, if this new system is a phone app, it'll just be using phone data instead, so it'd be hard for that to be intercepted.