I had an hour-long delay at PHL a few years ago waiting for the contracted mechanic (from Delta) to drive over to label a lav as INOP (can't remember whether it was duct tape or masking tape he used). Flight crew apparently aren't allowed to label the lav inop. I got the impression that Delta was very not eager to help Alaska out. I think this was a flight in which we had taxied to the runway and then went back to the gate to "fix" this issue.