Partner wants a bento box with cutters. I think we just pack too much for a 4 year old

Three weeks now of our 4 year old's lunch box coming back mostly full. Chapati rolls, idli, akki rotti, even her favourite lemon rice. She says she was busy. My partner's answer is a new box with compartments and shape cutters so the food looks fun. Maybe. My suspicion is less exciting: we've been packing what we'd eat, for a child who gets about fifteen minutes before everyone runs off. On Monday I sent half the usual amount and it came back empty. One day isn't proof. How much do your 3 and 4 year olds eat at school, roughly? Did a smaller box fix it, or did the novelty box work better than I'm giving it credit for?