There's not a form of transportation in the USA that is not heavily subsidized, so it's almost not worth bothering with. What roads do the buses drive on? What is the farebox recovery? What are fuel taxes? Who clears the bike paths?
Probably the only unsubsidized form of transportation is walking across a field, wearing down your own path.
In fact, some transit should be sold as enhancing the drivers; those people will never use it but everyone likes fewer cars on the road.
I agree with your last point, it's better to frame things as for societal good, because ultimately it's better for drivers that there's less drivers on the road.
However, I do take exception to your "everything is subsidised" argument; without even digging into it I can tell you for sure that trains have at least an order of magnitude less investment per km than roads do; and that's for existing infrastructure not to mention how much that lack of investment in new infrastructure has taken. -- Put another way: you can give me $1 and another person $1billion and claim that we both received money; the amount is important to acknowledge.
Probably the only unsubsidized form of transportation is walking across a field, wearing down your own path.
In fact, some transit should be sold as enhancing the drivers; those people will never use it but everyone likes fewer cars on the road.