Some travel agencies and companies act as "air consolidators" based on how much bulk air ticketing they do. To be labeled an "air consolidator" the company has to also sell tickets standalone. The more tickets a company sells, the better net rates they get - like any product really. Sites like Expedia are like a Walmart of ticket sales - their volume is high.

Airlines will offer certain companies and websites "special nets" that may not be exclusive, but also aren't always available to the public. Do keep in mind, those companies and consolidators will be adding margin's on those tickets to make money, and those margins can vary based on the company.

The other way airline consolidators make money of ticketing if not utilizing net rates, is getting commission of ticket sales. Large websites and travel companies will only pull in about 5-15 bucks a ticket sold, but it's a volume business and you'd be surprised how much it can add up to.

For a small and medium sized travel company, there is no substantial revenue in airline ticketing. However, including air and land arrangements with one company has great benefits and can offer savings.

In addition to the above, for a consumer - if one airline comes out with a low fare that undercuts a competitor on the same route, the other competitor will almost always match that fare in a specific class to stay competitive - especially on international routes. When I say class, i'm not referring to first and economy, but the ticketing class - each with specific restrictions (book by dates, travel dates, etc). I hope some of this made sense, a lot goes on with airlines and their fare structures with companies.

The competitive atmosphere of airfares among airlines is pretty interesting and wild - it is also not conducive to generating revenue.