You should know how the item is prepared, where it is from, and how it is stored. Other important information is the ingredients in the product and the nutrition of the item.
Vendor sandwich food production is required to adhere to local food handling safety standards. The sandwiches you would get from a vendor are generally safe and regulated by local authorities.
Vendor food sandwich production is usually made from cooks within the company. The company takes these products and distribute them to local outlets such as supermarkets and delis.