The answer is simple. Because a media buying service specializes in just that- media.
The traditional advertising agency places its salary emphasis on the creative department and account personnel. The media buyer, who often spends millions of dollars for the advertiser, is one of the lowest-paid people in the agency and often uses this training as a springboard to the more lucrative areas within the agency.
Because a media buying service pays top dollar for their staff, they attract the best and brightest media people in the field. The buying service is the one place an advertiser can be sure that the most experienced and the most innovative planners and buyers are handling his media dollars.
Broadcast time, unlike print, is negotiable. Because the media buying service buys time (radio and television) in volume on a regular basis and because a media buying service is a competitive purchaser of time, the rates offered by a buying service are lower - often 15-50% lower-than those of the traditional agency.
The buys are better and the planning is better. Because a media buying service deals with networks and stations on a daily basis, they have an ability to outperform agencies in both knowledge of what programming is available and how to tailor that programming to the particular needs and objectives of their clients.
Although print media is non negotiable, a media buying service can prove a major asset to clients in planning, providing detailed schedule and rate information, negotiating for prime positioning, advising clients on remnant space availabilities and trafficking.
Buying services, as a category, account for billions of dollars in billings per year. Today, accounts like Campbell Soup, Vick Chemical and ScottPaper are using these services with the knowledge that they are getting greater expertise at more cost efficient rates than ever before.