Earlier quoted context omitted.
Such buses are quite common in India too. Many people prefer sleeper buses even though the prices are similar to flights. One reason is that they have to travel to the airport (city a) and then travel from the airport (city b). A couple of interesting links: http://www.indiatimes.com/boyz-toyz/cars-and-bikes/sleeper-a... http://www.deccanherald.com/content/599348/scania-drive-1st-...
I'm wondering why airports don't try to monopolize airport taxi business. It's the logical extension of traveling from point A to B end-to-end.
In the DC area, there is a single provider of taxi service from Dulles Airport (IAD).
http://www.flydulles.com/iad/washington-flyer-taxi-service
Any other taxi service trying to pick up fares from IAD are violating the contract between the Metro Washington Airport Authority and Dulles Taxi.