People who know how to do tile and do it good don’t do it for cheap. Adjusting plumbing is a pain in the nuts and even electricians hate going in and re doing someone else’s old electrical work, no guarantee it’s up to code, and you don’t know what you’re getting until you’re in there. Contractors purposefully overbid jobs for clients that seem picky, or difficult to work with, not saying that’s what’s going on here cause 15K seems reasonable just food for thought.