Adam Smith reported this in the 1700s and has remained true to this vary day. In the days of Railroads, the Trains would have STOPPED running passenger cars except such service had been part of the law that gave Railroads the rights of Eminent Domain, that once the railroad was built, it would provide passenger service. The main purpose of Amtrak was to relive the railroads of this duty by transferring it to a Government Agency, that every thought would be out of business in ten years.
Plane travel has NEVER made money. The Airports were built by the US Air Force for its planes (and then used by passenger planes) or by local governments, The US Post Office subsidy in the form of Air Mail was critical for most Air Lines prior to WWII AND remains a subsidy to this day (Mail goes by air on a space available basis, thus if the plane is empty, mail fills the empty luggage holds).
Greyhound has barely stayed in business, and again its terminals tend to be built by local government OR on sidewalks on the side of the road. Even the low cost buses depend on using local sidewalks as pick up points.
Sorry, Passenger transportation has NEVER paid for itself, it has to be subsidized somehow. This subsidy may be direct, like paying someone to provide the service, but mostly indirectly, as in providing money if no passengers show up OR by requiring someone to provide the service even if they lose money on the service (The Railroads were the classic example of this) OR by providing much of the costs incurred by the provider (as in the case of Buses and Planes where the roads and airports they use are paid by someone else).
Thus the proposed "Google Bus Model" will have to be subsidized somehow, and when it comes to direct subsidies you will face massive resistance (Thus indirect subsidizes have always been the preferred means of subsidy).
The one exception to this rule MAY be the old Steam passenger ships, but in those ships the cost of providing the 1st, 2nd and 3rd class passengers, passenger service was borne by the sheer profit made from the people in steerage. In Steerage, sanitary facilities were barely furnished and nothing else was (Steerage had be bring their own food, and cook their own food). Steerage was cheap ticket and you were pack like sardines, but it appears to have been profitable, through even that service was "Subsidized" by businesses in the US bearing some of the cost in exchange for first chance at hiring any new immigrants.
When immigration restrictions were imposed during the 1920s, all of the old ships ended up being scrapped for without steerage passengers they could not be made profitable. Passenger service had become so unprofitable by WWII that almost all Passenger Ships built in the 1930s were built with Government Funds or backing (This was justified on the grounds such ships may be needed as troops transport in time of war). The US United States was built by with assistance of the US Navy, in case the Navy ever needed it as a troop transport. By the 1950s Air Traffic finally killed off the transatlantic passenger ship and most ended up as cruse ships in the Caribbean, again NOT as passenger ships but vacations spots in themselves.
Sorry, a Google type system would need a direct subsidy to work and right now there is no support for such a subsidy (and no support for a one Dollar a gallon tax on gasoline, for that would also act as a subsidy to mass transit in the form of increasing the costs of driving while the cost of taking mass transit would remain the same). Without some sort of subsidy, direct or indirect, passenger service can NOT be profitable and even the Google type transportation system has to at least break even.
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