Successful hills are here to stay. Everything must be this way.The Doors, "The Soft Parade"
We've got two lines from "The Soft Parade" by the Doors, a really famous band from the 60s and 70s. The rest of the lyrics to the song are super weird and abstract, but these two lines definitely fit in with the message of Tangerine—in two ways.
"Successful hills" are basically what Lake Windsor Downs is—a fancy-schmancy neighborhood where wealthy, successful people can show off, where appearances are everything, and where materialism runs rampant. It doesn't matter what the dark truth is, whether about the burned-up and buried tangerine trees under the development, or the cruelty of the people who live there. As long as everything looks nice and uniform on the outside, it's okay. "Everything must be this way." Paul's mom would totally agree, and she would also hope that they were "here to stay."
In the end, nature seems to be winning. People manipulate the environment to create developments like the one Paul lives in, and ignore geological realities to build middle schools—but the land isn't going anywhere. If there's supposed to be a forest, and you cut the forest down, then the land is going to fight back. If you build a middle school where there shouldn't be a middle school, the earth is going to swallow it.
So. Which interpretation do you think first best? Or is it both?