That's a really great analogy, actually. You can't tell a brand-new cook "salt to taste," but you can tell a cook with an intermediate level of experience "salt to taste" even if it's a recipe they've never made before. You can't impart the experience in words, pictures, or symbols. You can't add a chapter zero that gets them there. But the right kind of experience will get you there pretty quickly.
I admit it's kind of frustrating that it can't be boiled down to a list of discrete things you need to know, but if I had to explain the difference between me before I had "sufficient mathematical maturity" and me after, I would explain it in terms of habit and confidence and other squishy things that aren't mathematical at all.
Giving a precise value for this doesn't work in any case. "Salt to taste" is inherently qualitative.
Most pizza dough recipes quote around 5g of salt for 250g flour. Personally I prefer double that amount, and this is the case with many recipes.
Perhaps specifically with salt there is an insane amount of paranoia about blood pressure. In many ways it feels as irrational as Korean worries about fan death.
On the other hand, giving a "5g of salt" value is a good starting point, to avoid undersalting due to paranoia or oversalting due to inexperience.
What they really need is someone to tell them to add less than they probably need, then taste, add more, taste, add more, and expect to over-season and under-season some dishes as they get experience. Salt quantities in recipes have to be short, sometimes way short, so you're stuck learning the process with or without the quantities. I've never seen this explained in a cookbook, at least not in a way that made an impression on me.
Edit: A piece of advice that has stuck with me for a long time, long after I forgot where it came from, is it's a mistake to look for the state in between "not salty enough" and "too salty." That state doesn't really exist, especially when you're feeling nervous! Instead you should look for the overlap where you can perceive the dish as alternately "not salty enough" and "too salty," like that ambiguous drawing that your brain can resolve to either an old woman or a young woman[0]. That advice really works for me, but my wife, who seasons like a pro, thinks it's nonsense, which I think illustrates how subjective the process is and how it isn't information you can impart but rather experience you have to guide someone toward.
I admit it's kind of frustrating that it can't be boiled down to a list of discrete things you need to know, but if I had to explain the difference between me before I had "sufficient mathematical maturity" and me after, I would explain it in terms of habit and confidence and other squishy things that aren't mathematical at all.