Any child will be interested in getting something to eat from the School Canteen. Perhaps all the others bring money.
It is not such a bad thing to take a small amount of money to school. You could lay down some limits, like how much he can spend at one time. It may help him to take responsibility. But you should also make sure that he does not buy only potato chips every time. If it is something cooked in the canteen, it is likely to be better for health.
You could try out giving him some money and see how he handles it. Discuss it with him and let him see that you are reasonable.