It's not just about welfare, its also about political power. For example, New York houses tens of thousands of prisoners from New York City in various upstate prison towns. The population of these prisoners is counted towards the populations of these upstate towns, even though the prisoners cannot vote and aren't from that area. For purposes of gerrymandering, funding, and anything else related to population these prisoners are literally political ammunition. This added clout puts representatives in the statehouse that exist only to flood the prisons with more prisoners, completely beholden to prison guard unions and other prison-related industries. They spend their time blocking any sort of logical criminal reform, marijuana legalization, or anything else that would slow the steady stream of prisoners. Its a corrupt system to the core.
Prison gerrymandering has been reformed in a few places, particularly New York. Due to reforms passed in 2010, prisoners are now counted toward their home districts.
California has likewise passed a law to discontinue the process there by 2020.
For much of the rest of the country, this is still a problem.
$168,000
http://mobile.nytimes.com/2013/08/24/nyregion/citys-annual-c...
Average in the US:
$31,000
https://www.vera.org/publications/the-price-of-prisons-what-...
This isn't about justice. It's about prison guard jobs. It's about welfare.