And sure, the conditions you describe are unimaginable there. But there's more to the world than the Glorious USA and subsistence farming at $5/month.
You are setting the bar waaaaaay too low. There are many shades out there. There are plenty of countries where the opportunities are much more scarce than in the US, but which nevertheless got a lot of things right that the US got wrong.
And you can make your own "real developing country" definition, just don't expect others to know it. Probably for the best to just name the country you have in mind.
[1]https://en.wikipedia.org/wiki/Developing_country#Developing_...
[2]http://worldpopulationreview.com/countries/developing-countr...
Perhaps you mean "least developed countries"[2]? That's beside the point, however.
The point is, making up definitions and using the equivalent of "love it or leave it" when it comes to talking about the US won't get you far in terms of getting any point across.
And I didn't say "love it or leave it", I asked a question. People who hate where they are, complain about it incessantly, compare it to things they've never experienced in order to denigrate it absurdly, cons the fuck out of me with why they stay.
You're speaking from a position of such great privilege that you don't even have a frame of reference to accurately talk about a developing country. They're leaving because they would rather make 500 dollars a month working 20 hours a day at three jobs in Dubai than make 2-5 dollars a month working 20 hours a day at subsistence farming or worse, and they're often doing it so they can support those back home who don't have the skills to find sponsorship to work abroad.
They learn a skill that will let them leave, or they find an agency that is hiring people to work abroad. I know plenty of people who have left their country to find jobs elsewhere -- many of them in the US, many in Japan. Any good nurse from southeast Asia who wants a job can usually get sponsored to come to the US -- there are other professions as well, some in the US and some elsewhere.