Do you mean pedestrians using phones? My first thought was drivers using phones which I see regularly and would be a risk to both pedestrian and cyclist.
Or is the answer simpler than that - is it the rise of SUVs which don’t have to comply with normal vehicle safety standards?
The answer the answer is honestly much more complicated than either.
Some is increasing vehicle size and weight that make crashes more deadly to pedestrians. Some is road design that encourage unsafe driving habits, as well as designs that are actively dangerous to pedestrians. Some is new distractions for drivers.
Phones
Phones, automatic transmission, so we have a free hand to use the phone, and huge dangerous roads built with no care for pedestrian safety.
It’s no single thing, but a mix of things that feed on each other, and create a terribly dangerous situation. 
Also, huge truck and SUVs and the demand for them is ever increasing.
Are phones also causing the simultaneous increase in cyclist deaths? Obviously not.
Or is the answer simpler than that - is it the rise of SUVs which don’t have to comply with normal vehicle safety standards?
Do you mean pedestrians using phones? My first thought was drivers using phones which I see regularly and would be a risk to both pedestrian and cyclist.
The answer the answer is honestly much more complicated than either.
Some is increasing vehicle size and weight that make crashes more deadly to pedestrians. Some is road design that encourage unsafe driving habits, as well as designs that are actively dangerous to pedestrians. Some is new distractions for drivers.