> why on earth do you build chemicals plant that have a risk to explode near habitations ?!!

At least part of the answer -- at least, here in Texas -- is "because you can." Lax or nonexistent zoning laws have long exacerbated damage caused by industrial accidents, a posture state lawmakers continue to defend because it is seen as "pro-business." [1]

It seems to me this is simply socializing the externalities of running, say, a fertilizer or organic peroxide plant, but that seems to be an unpopular view statewide.

1. http://www.nytimes.com/2013/05/10/us/after-plant-explosion-t...