As someone who lives in a place where cycling traffic (i.e., completely silent traffic) is massive (Amsterdam), I would suggest this is just a matter of careless habit in a car dominated society.

The only people not looking, relying in their ears and therefor constantly causing dangerous traffic situations over here are tourists. Those are the only ones blindly stepping into traffic because they don't hear the bicycles coming and therefor assume there is no traffic.

The need to have traffic go "vroom, vroom" in order to avoid accidents is just pathetic, and utterly unsustainable in a future where all traffic is likely to be silent by nature.

Imagine living a place that would be as nice an quiet as a village on a sunday if it wasn't for all those vehicles creating artificially amplified noise pollution. Ridiculous.