Let me click on a line while using GUIDED perspective transform

Actually, this is probably an example where the proposed tool would be an improvement. It's indeed very strange that the auto upright tool fails with this image, because the lines seem to be clear enough. If you could simply click on both sides of the shed to set the two guide lines for Guided Upright, then that would be a lot faster than placing both guides manually. 

Exactly. To true up an image with all four guides takes about 15 seconds. Four clicks near an edge would take 2. 13 seconds per image, 5000 images per year is a savings of 18 hours. It would be a large improvement if there was simply an addition of “snap to edge” option.

Yes, but like I said earlier, this is the odd one. Normally an image like this could be corrected with one single click on Auto Upright button. That is even faster. And images that fail in Auto Upright would often also fail in some ‘Auto Snap to Edges’ guided version, for the simple reason that the same technology would be used to detect the edge that you clicked on. So your math is probably far too optimistic.

Meh. I can say with absolute certainty that the Auto modes have been 0% successful. I shoot architrcture. Almost correct doesn’t fly.

You keep missing my point. If auto detect of the lines fails all the time (as you claim), then auto detect a line after you pointed out that line will also fail. The algorithms apparently aren’t good enough.