It is sad but true that parking in U.S. cities is badly managed and so is public transit. When you put them together, the difficulties multiply.
Here is the Seattle story of parking poachers (h/t Patrick Sullivan). Put underpriced parking next to underused trains and planners have to start looking at parking rate hikes to balance the two. But that might turn away some transit riders which would further reduce train use.
The story in Denver is slightly different. Here is the WSJ's report on how and why park-and-ride lots have taken up real estate that could be used for transit-oriented development. Which is better for transit use? Very tough question.
I attended a conference some years ago (cannot recall which one) where a speaker noted that one of the Northwestern states or cities or counties (again, not sure) had welcoming poster that included a picture of a bear snaring a salmon out of a mountain stream. The speaker wondered which side an environmentalist would be on. Also a very tough question.