Because college students have no income and are sensitive to fruit prices, they will buy cheap fruits. There are many fruit stalls outside the university gate, and there is fierce competition between them. After the price reduction, in order to ensure that you still have money to earn, you can only make a bad idea on the weight and deduct one or two to earn one or two dollars. However, college students' awareness of rights protection is generally worse than that of inspection. Even if I go back to argue with the stall owner, I will only return the goods and refund the money at most, and the stall owner will have no loss, which will reduce the cost of their shortage, so they will become more fearless. In the final analysis, it is caused by the lack of credit system and imperfect market management.