When will I learn?

You know, I've been burned over the years several times by doing job references, recommending people or places for different things, etc. Well, once again, I've been nailed, but good. A friend of ours teenage son does odd jobs to try to earn him some dating money, and has cut grass for folks and tinted car/truck windows for several folks, and was actually supposed to tint mine and Wayne's, and had done a great job to this point... Here's where the bottom falls out. I recommended him to my cousin, Tonya, who called him and had him come tint her truck windows last week. Well, when we got home from the coast on Sunday, she was calling Wayne to warn him not to get his truck done. His price was fair, no arguing there, but he'd managed to miss the side of one window with the tint, squish the rubbers around the windows, scratch up the plastic and a place on the door (that will have to be re-painted), and one window wouldn't even go down. She was quite upset, understandably. But, instead of calling him to come back, she was just going to eat the tint fee, have it fixed, and call D-Dot to do it right. Well, she took it to Baxter's yesterday... drum roll, please... repair estimate = $700! One of the window mechanisms is broken and the part alone is $400. Quite upset doesn't even begin to cover it. She did actually call the boy back, who wanted to bring his dad over to look at it. 'Course Baxter had "rigged" the window temporarily, and it will go up/down, but not for long. I don't know what will come of it all, but feel so bad having been the one to initiate things... Why don't we ever learn?