There are lots of reasons people shoot in black and white. For me, the elimination of color focuses attention more on shapes and shadows.
In Fence and gate, the use of black and white emphasizes the shadows in the image leading the viewer to the gate. It also brings out the vertical lines in the building, which almost acts as a barrier to where your eye wants to go.
It’s also a “busy” photo: there are a lot of elements in the frame. The use of black and white helps bring out these elements. If it was in color, the image could potentially be too busy.
Using b&w, in this case, helps emphasize what’s important in the image.