So we subsidize the employment of prisoners to help with their reintegration back into society. I don't see the problem.

Hell, so long as it's effective, we're saving money in the long run. Money spent curbing recidivism pays for itself, considering a prisoner costs tens of thousands of dollars a year.

Also, it's not like prisoners are competing for the best jobs. There are heavy restrictions on their employment (part of why a strong incentive is needed to make them employable) so they are unlikely to be competing for software development jobs anytime soon. They do things like clean roadsides and stamp license plates.