Human perception is highly non-linear and largely based on the concepts stored in the brain. Trying to manually approximate that with math is bound to fail once you approach certain fidelity threshold. If you look at the recent color science and spatial perception research, it becomes obvious that it makes total sense to mass profile the perception and throw ML at it. A lot of researchers are still in denial about this, though.

Agree with sibling comments. There's something very slippery and tricky going on with "perceptual area," it's not simple geometry. This is actually an area where I think machine learning has something to offer.

There have been lots of attempts to automate kerning for decades. Most people seem to agree that they're still inadequate and that manual adjustments produce the best results.