> The bigger issue is that city planners building public transit systems don't have the same interests as commuters. Inevitably they want to use public transit as an instrument for various social policies.
Here's the thing: public transit does not function in a vacuum. You can't build public transit solely based on current traffic patterns, because the presence of good transport (say, a new rail line) will irrevocably alter traffic patterns.
This means that, if you build a new rail line, you pretty much have to (eg.) change zoning near stations. Is rezoning to allow denser housing "an instrument for various social policies"? Most likely yes, but it's also the sensible thing to do!
Here's the thing: public transit does not function in a vacuum. You can't build public transit solely based on current traffic patterns, because the presence of good transport (say, a new rail line) will irrevocably alter traffic patterns.
This means that, if you build a new rail line, you pretty much have to (eg.) change zoning near stations. Is rezoning to allow denser housing "an instrument for various social policies"? Most likely yes, but it's also the sensible thing to do!