The girls of "Teen Moms 2" do get paid. Nobody does a TV show for free anymore. The girls on these shows get a wage, that ranges from $60,000 to $65,000 per season. That is more than they could earn, working at a regular job.
It is a partly scripted show. They are making these kids act like they are struggling to get by, even though they make more money than my family. They are not a good place to look for advice, and you can do better with your entertainment.