I'ed say she should continue with it and she will learn so much about care and empathy which is what nursing is all about. as well as having hands on experience to complete projects etc. The role of care assistant is usually hard graft especially because she is actually doing the job and has to have her wits about her for a full shift as the person responsible to the nurse. As a student she is not doing the job, she is learning and on a placement with partial duties mostly "shadowing" and observing, which also does not include non-nursing duties like heaven forbid, dressing beds etc. when she is the nurse she can expect it to be as tough as a care assistant, as she will have the ton of paperwork to boot.
Its a great lesson for her though. She will fully appreciate those who work with or under her direction. She obviously thought the job of care assistant was easier than it actually is, and as they say sense bought is better than sense taught.