Is it legal for supermarkets, postal insurance companies and other enterprises to sell travel products of a travel agency as agents? Why?

The direct understanding of agent sales is that all products that are not produced and sold by themselves can be called agent sales, and all products that are not produced by themselves can be called agent sales. For this concept, we can cover many aspects of life, such as dealers, agents, specialty stores and shopping malls. A product belongs to a product in a factory but not a commodity. It can only be called a commodity if it enters the circulation. The popular concept of consignment now, many people mistakenly think that it only refers to online consignment, which is a very narrow concept. The further development of online consignment is only the evolution of the concept of consignment. For example, in the real economy, you can negotiate with physical stores, how much rebate they give you when you introduce a customer, or a part-time salesperson of a company, and so on.