Business travel, the requirement to visit prospects, clients or manufacturers, etc., is historically an important part of any business that has clients or segments of business geographically spread out. These costs, especially airfare and hotels, can be great.
Frequent flyer programs for airlines are not much benefit for a company because those miles are associated with the person who flies, not the person who pays. In a sole-owner situation this is fine, in the case of an employee flying, it is a benefit to the employee not the employer. Larger corporations contact with travel agencies to get group rates and efficiencies of scale but this only applies to the cost of the travel service, it has no influence on the cost of the ticket itself.
The internet, through video conferencing and especially email, has reduced the need of some businesses to visit as often as they may have in the past.