The employee should have told her about that at registration. I'm just surprised Lill hadn't been robbed earlier.
Is she still living with her abusive parents? Chapter 2 made it seem like she wanted to move to an empty hut but was talked out of it and to my knowledge we haven't learned anything about her living situation after that.
It'd make it strange for her to always carry around all her money to keep it away from her parents, as they could just easily take it at night.