They're complicated because they involve so many people with different interests and points of view.
A minor problem in my city involved a few acres of land that had been given to the university to be left natural. The environmentalists wanted to preserve this land. However, using this land for industry would help businesses and provide more jobs -- something much needed in this area.
Why are finding solutions to environmental problems so complicated?
2 answers
Because it is often expensive for people with great political power to clean up. They and their lawyers invent all kinds of reasons not to address the problem. On the other side are environmental organizations which are sometimes themselves under the financial control of the polluters.