It's an opt-in arrangement.

This is part of a plea bargain. She had a choice of three months in jail or one month in jail and two months working a fast food job. She had a choice between a "normal" three month sentence or this "unusual" sentence.

And yet we allow Chipotle to treat its workers like that anyway.

One could make the argument that working fast food is less cruel than spending 3 months in Jail. If you claim that fast food is worse then she kind of deserves to make that realization herself.