People who are struggling tend to get the hand-me-down previous-generation devices for nothing or next to nothing, and you don't really need the $30/mo data plan. Older devices are also quite cheap when bought incrementally as part of a phone plan.
For example, I know someone with an iPhone 6 that cost them nothing, and a USD $12.50/mo plan, with unlimited calls and several gigabytes of data allowance.
I agree with you that not everyone who is struggling is able to allocate $30/mo, or even $12.50/mo, but it's low enough that if it's a very justifiable expense (and I would argue that communication and internet when you have to sit or walk every day on the street is extremely justifiable), that level does not impact someone's food consumption enough to justify a random passerby judging they are secretly faking povery.
Spending $1.00/day or $0.40/day on something you'd consider a luxury item, does not mean that person is faking poverty, at least in the US.