There are some transit systems whose subsidization approaches or perhaps exceeds $15/passenger mile. Most, however, are nowhere near that bad.
Interestingly, the London Underground is a consolidation of transit systems that were built by for-profit companies. Yerkes' company digging the deep tunnel lines (central parts of Picadilly, Bakerloo, and IIRC part of Northern) went broke, and was intended to be subsidized by the surface rail (which makes sense, since an underground connection increases the value of the surface-rail line) but nonetheless was privately financed by people who wanted to make money.
Compare that to the public-money boondoggles of today.
The worst is the private chauffeur services that the liberals have enacted for the elderly and disabled. I have no problems with designing public transit systems so that they are accessible by people who need special consideration. But it should still remain economical mass-transit for large numbers of passengers. Not personalized door-to-door service for a few.