Why do the white Out Of Bounds markers on the left of the 15th fairway end before the diverted footpath?

The Out Of Bounds (OOB) markers are to indicate the actual boundary of the course. Consequently, the OOB markers to the left of the 15th fairway stop at the point where the footpath enters the course and runs behind the 7th tee, as this is all part of the the course. The boundary of the course also runs along the left side of the 7th hole. If you extend a line from this boundary, across the footpath, it will meet the boundary on the left of the 15th hole at the position of the last OOB post.