I tried zorin's perspective correction in Paintshop Pro, and the result looked like this:
On the right after some further post-processing. The proportions look broadly similar to Photoshop.
I had often the issue with that correction tool that the resulting image was too tall, though this may have something to do with the kind of image I typically applied this too.
My gut feeling is that the tools treat perspective correction as a 2D problem, levelling first one line, and then adjusting the other line with an affine transformation. I wonder whether viewing it as a 3D problem would yield better results, or whether it really boils down to the same thing...