Well... I guess that the answer to that ¿why? that you are looking for is not a simple answer.
My guess is that there is not enough thinking on the long run or that historic memory is so short that nobody cares. Or even simpler than that, mankind is stupid.
In Spain some years ago there were around 15 people drowned while they were sleeping on their tents and caravans on a camping site.
What happened was that the camping had been built on an dry watercourse.
The stupid thing is that they got all the permits to build it there and they knew it was watercourse but as it had been dry for about 60 years nobody cared.
Only the oldest people of the village remembered seeing water coming all of a sudden on a sunny day, that water came from some mountains about 20miles away from it where there had been a heavy storm, but... who listen to old people nowadays?
What happened was that there was another strong storm on those mountains at night, and all of a sudden a wall of water and debris came down roaring and wiped away the whole site while people where sleeping in their tents and caravans. But of course... who could have imagined that
I let you put your own comments...