As for the last point, it's not too difficult with one case, but with more than one you'll need another pair of hands.
Ok. But that proves the point, staff end up having to push a passenger in a wheelchair and pull a case at the same time, when many Tocs if not the majority state that staff should never push a wheelchair and pull a case at the same time. But in practice the job requires them to do it, so they (the staff) take the liability. If there was ever an accident the company would probably say we briefed you not to do that and you chose to do it and you are to blame.