This morning's WSJ includes "Rail Lines Bring Housing Clashes ... Cities Take Steps to Promote Affordable Housing While Rents Rise Near New Transit Stops."
Those who comment on the economic problems of the EU point out that a common currency and and independent fiscal policies (politics) can clash in a big way. One cannot have both. And this simple trusim is how we got to all the head scratching and the occasional hand wringing.
If your transit policy requires a transit-oriented development policy, then there will be consequences for the low-rent housing (and occupants) that had been in place. Planners embrace and also scorn gentrification.
How to escape the conundrum? The answer has been to subsidize favored developers and coax them into including quotas of new but affordable housing units in their projects. This enriches certain developers and solidifies city hall crony capitalism.
On a bad day, it also takes some developers and some development out of the picture, causing housing to become more expensive. But when people move out of central cities, dysfunctional city government (including public schools) as well as costly housing are often in the mix
Fixing a policy error by piling on more policies is never promising.