Eventually this could be put into place in the broader traffic ecosystem - if all the cars on the road were required to have a transponder sort of arrangement on board, you could have a central point of control, and perhaps tie in people's phones etc to locate pedestrians. I do want to note that I am aware that there is an unfathomably large amount of complexity behind that however.

There's a movement towards this; look up "Vehicle-to-Everything" or "V2X". The idea is to enable things like one vehicle transmitting sensory information or intent to others around it, helping to prevent rear-end collisions, etc. My personal take is that it's well intentioned, but there will always be things that aren't part of the corpus of communicating devices that will then limit the utility. I suspect the communication of sensor data is the more useful part than some of the demos I've seen so far of, for example, a car sending an alert to a person's phone so they don't step into a driveway when it's reversing.

Because my dog will totally have his mobile phone on him when I'm chasing him down. Or my little kid chasing after his ball...

And when software on a car assumes pedestrians always have a mobile device on their person, charged and ready for a split second alert? IMO This would be an absurd design.

It'd be a tool in the toolkit, in my hypothetical. I mean, by the time autonomous cars were common enough on the road, we might all be tagged with an rfid chip as a normal identification or something... I don't disagree that it's an absurd idea, but it's just a devils advocate position I'm discussing here.