You can quantify things like sweetness or even presence of certain aromatics. If the technology to do this was tricky 80 years ago, it's much less so now.
Whether that would be helpful or not, I don't know. In part because...
> people like the color red.
It's actually an example of HN favorite Goodhart's Law: "When a measure becomes a target, it ceases to be a good measure."
You can't taste an apple before buying it, usually. And certainly not the specific particular apple you are picking. So people have to pick based on qualities like visual appearance or firmness (or in some cases smell, but that's less helpful with apples than with some other fruits). A nice bright red apple was at some point, at least with some varieties, taken as a good proxy for good flavor/soundness.
Until growers, to take advantage of that, started breeding for color at the expense of flavor. Goodhart's Law.
People like an apple that is not rotten or diseased and tastes good, they were choosing red color at the market hoping it would represent that when you can't cut open an apple before buying it. I don't think most apple consumers actually prioritize color over taste.
