[gavinsyancey]

* Disruption while it is being built

* Fear that a metro will bring in "undesirables" (i.e. poor / lower-class people)

* Concerns about noise (whether real or imagined)

* Some people just hate change

[frollogaston]

The "undesirables" they're concerned about are robbers, teenage gangs, or people on drugs who loiter around train stations. The lower-class people don't want to be around them either.