TURSAB are the Turkish equivalent of the National Tourist Board. They licence and control all pensions, guest houses and hotels. They also control the licencing of all transfer companies and their staff operating in and out of the airports. They have the power to stop anyone entering the airports at the gates.
If you look at the coaches and buses entering and leaving the airport you'll see that they display a board in the front window with the name of the tour operator and a crest. The crest is that of TURSAB and is the licence to operate.
They ARE legal and the Turkish government made them so.
Apparently they have begun to crack down on unlicenced transfers at Dalaman. If you stand there with a piece of paper with the persons name on , then by their reckoning, you aren't collecting a friend or relative, so you must be operating an illegal transfer business.
No doubt others will add their comments, but this is roughly as it's been explained to me in the past.
