答案 0 :(得分:1)
The fold arrows that Sublime adds to the gutter only appear based on the indentation of your code; specifically there needs to be at least two lines below a line that are both indented (how much indent doesn't matter as long as there is any) for that line to gain a fold arrow.
As visualized in your screen shots, there is no indent and so you're forced to use manual key bindings in order to fold code.