I think by seeing a single incident making a general statement may not be correct. Why should a 10 years boy should be respected by the seller. He is a boy without any financial independence. Again that dependence on the relation between the shopkeeper and the buyer's family. Tomorrow if the family questions the vendor he may not be able to give an answer.
I know many people in the society respect old people. In my native place my parents stay. The villagers help them in all ways. While going out for any purchases the neighbors will ask about our parents requirement and bring those items. Father will give them the cash. If my parents require anything they phone up to the shop keeper, he will send all the material and take money from father. Everybody in the village respect them. Respecting a person depends on the behavior of the individual also.