Not if they go unused or underused, or otherwise end up being less efficient and/or more costly overall than the alternatives. Then it's worse of both worlds.

Not if they go unused or underused, or otherwise end up being less efficient and/or more costly overall than the alternatives. Then it's worse of both worlds. Theoretical efficiency and real-world efficiency are different things. Public transit isn't inherently good by virtue of existing without real-world benefits. (To assume or believe it good without proof would be dogmatic faith, not science.) And those benefits gained need to be greater than any and all offsetting costs lost. There are far more real-world scenarios where busses and trains end up being far less efficient than driving and flying than vice-versa. The difference in logistical degrees of freedom between the two sets makes bus and rail far too reliant on ideal geographic and operating conditions. Yet it's always these few ideal scenarios that are the basis for most cost and efficiency comparisons & claims, and are what get presented as justification for building/implementing. And the countless public transport systems that never get the ridership or revenue that their pre-construction cost/benefit analysis or environmental impact statements predicted is proof that they rely on overly optimistic assumptions that rarely pan out.