About 48% of the human population owns a smartphone (that doesn't include "feature phones"). 85% of American adults own a smartphone. 97% of Americans own a cellphone.
Lots of people can live without running water, sewer, power, cars, hygiene products, etc. but that doesn't make any of it practical in modern society in the US. There's of course a limit to this as to where the baseline is, but I'd say having a portable phone of some sort and internet access are pretty high up on that list.