It's only easy if you have the ability to control all of the inputs. In this case we don't even know what those inputs are, let alone the ability to control them.
Eh, not quite. It’s fairly well-understood what is used to determine a credit score and basically how all that information is compiled.
1. How much money do you make?
2. How long have you been making that much?
3. Is your income irregular?
4. Have you ever taken out a loan? When’s the last time you did so?
5. Have you ever failed to pay back a loan?
6. How many loans do you currently have open?
7. Are any loans behind?
8. Do you have a revolving line of credit (credit card)? How many?
9. How much of your revolving credit is in use?
10. Are you late in paying any of your credit lines?
And I’m sure there’s more stuff I’m missing. But broadly, if you’re looking to get credit/loans, banks prefer someone who a) makes enough money to service their debt, b) doesn’t have too much debt relative to their income, c) pays their bills on time, and d) has an established history of a, b, and c for an extended period of time.
Creditworthiness is not a mysterious algorithm that few can comprehend.
Seeing that your first three points have nothing to do with your credit score and aren’t captured by credit agencies, you’ve kind of demonstrated that it isn’t well understood.
Credit applications usually just ask for your income. They only verify it my experience sometimes for car loans and only for the last month and they only go back three months for verifications for mortgages.
They're both considered "top" credit risks, but obviously one of the two people has demonstrated a longer history of being such trustworthy person to lend money to (also probably makes a lot more money than the other person to boot). It's not at all uncommon for people with "identical" credit scores to have different limits.
Now perhaps there's an argument to be made for more granularity in scores to make something like this more obvious, but it is what it is.