I can't make eye contact with a driver who's not looking my way, and it's not my responsibility to delay crossing the road for drivers who DGAF. Perhaps the proximity sensors do make a loud sound, but I've found that yelling 'hey' or hitting the car is sometimes the only means of getting some drivers' attention. It seems to me that if someone wants to operate a large heavy machine on wheels it's their responsibility to be alert while they're operating it.
It is indeed reasonable to careful since a motor vehicle easily outmatches a person, but if you look upthread my original point what many drivers are careless, and the cool technology like peripheral cameras does not always mitigate that.
I think that the trend towards larger vehicles may exacerbate the number of casualties caused by careless driving, and I wonder if all the safety features unintentionally foster a sense of complacency.