Like all brand names, SuperShuttle thrives on recognition. You're traveling at a mysterious airport and know what to expect from SuperShuttle as opposed to Crazy Achmed's Airport Express...

... except that they don't enforce their brand well at all. Some vans are operated by the company, others by franchisees-- so you may actually be riding with a CAAE driver after all-- and their quality varies. Coordination between the two is chaotic or nonexistent (at least, I experienced quite a circus trying to get to AUS after a conference). I don't know the mechanisms whereby airport vans are regulated, but the number of times I've ridden with a lost driver suggests they are not as stringent as taxicabs.