jobs that there literally aren't enough jobs available.
Sure... the service industry can grow.... but what is going to happen when all taxi drivers and truck drivers are replaced by driverless cars? And fast food workers replaced by robots and ipads?
It's completely conceivable to think that enough low-skill/low IQ labor can be replaced/outsourced that there simply won't be any way for them to provide for themselves.
So to keep them from turning to a life of crime to provide for themselves, we can pay them a living allowance and meet their basic needs.
We certainly don't need it now... nor will we 10 years from now.... but perhaps we do in 20?