Suppose you are a bit of a bastard and also a tightwad, and would prefer not to keep spending money on food, accommodation etc for a slave who was frankly always a bit of a lemon.
You aren't allowed to kill them, Hadrian outlawed that. Your slave has no marketable value.
What do you do?

Comments
I imagine most people would have been in a sort of modified family relationship with household slaves, so a beloved slave might have been well treated (assuming the owner could afford it), and an unbeloved slave over worked, under fed, and neglected.
Non-household slaves, though, must have been treated like animals. Or machines...
I wonder if Claudius's ruling was a bit of a let them eat cake solution? What use would freedom have been to an abandoned slave?
I keep coming back to something I read about an elderly Anglo-Saxon woman who sold herself into slavery because her husband and children were dead and she had no other way of supporting herself. What work would she have done? Maybe there was something feudal going on, and 'slavery' in that context was like getting the dole, and you paid for it with a fall in status?
But yes, if the slaves were not able to work again, I'm sure freedom was no great benefit to them!
I read that injured slaves were often given work as childminders, but surely there must be a limit to the number of people who could be reasonably employed doing that.