I guess the brick and concrete border was a little too small, and the tree just ignored it and kept growing. Tree: 1. Landscapers: 0.
And the neighbors, bless their hearts, didn't try to remove the border -- they left it intact as the tree continued to grow and raised the border higher and higher.
It's wonderful -- makes me smile every time I walk past. It reminds me of a great David Wilcox song, Leave It Like It Is.