As someone who only reluctantly got their first smartphone in the past year (yes, I'm a computer programmer, I dunno), I can say that cheap flip phones don't really exist anymore in the US. You can generally get a cheap smartphone cheaper than a cheap fliphone, in 2019.

For instance, you can get smartphones for well under $50 from Cricket, once every 90 days per account. They are locked to Cricket, but you don't actually have a contract, you can abandon them at any time with no penalty. Yes, the cheapest smartphones are gonna be _really bad_. But in the past year-ish, perfectly usable smartphones available around $100-$160 became a thing (carrier locked but no contract). (Flip phones have become _really bad_ too though. Flip phones available in 2019 have worse battery life and worse performance/UX than flip phones of 5 years ago. like press a button wait 1s+ for something to happen bad UX)

Flip phones are pretty much gone, I don't think they are a thing poor people use anymore. They might be a thing old people use, or that people attempting to have an anonymous disposable phone use. They don't generally make sense any more as a cost conscious thing, plus if you're poor you don't want to be reminded that you're different from "everyone else" everytime you look at your phone. Incredibly cheap (crappy) smart phones are available, and relatively affordable reasonable ones too.

(Plus, not just for poor people these days, but especially if you're poor, your phone is probably your only computer and only internet access).