On the opening repetition they are present to find the position to jump back to easier, since the normal thicker bar marks tend to be too unobtrusive. (Probably not required if only a few bars are repeated.) On the closing repetition they may help to remind to repeat. So actually they are only useful in the single part (in the full score the long brackets should be easy to see anyway). The are always leaning towards the range of repetition, the crossed example in the trio seems weird.
I find, that if not present in the printed part something similar is added by the performer with a pencil.