In the USA, what builds credit scores is showing a pattern of using revolving credit and servicing the debt over a period of time. You are penalized if you use too much of your available credit. You are also penalized if you use too little of it, as I found out when I paid off the balance of the one remaining card that held a balance, and saw my credit score hit by about 15 points shortly thereafter. There are other rules, too.
Basically, I can only conclude that we are encouraged to be 'good citizens" by borrowing money and paying interest on it while slowly paying back the principal. People who live on a cash-only basis, which was considered to be a respectable practice not that long ago (borrowing was shameful) have terrible credit scores.
So what, you may ask?
There are very real and increasing disincentives to having bad or no credit. Creditworthiness (in the form of a nice, easy to understand number) is being taken more and more by various entities as a sign of responsibility and even good character.
A credit score is now used by some entities, beyond the mainstay car dealers, to judge risk and character: apartment rentals and employers, to name two.
I'm not suggesting that all employers and apartment management companies do this, only that the trend (I have no citations but it should be searchable) is on the increase.
The bottom line is that in the USA today, credit scores depend on how - and how much - you borrow and repay.
Furthermore, the higher your credit score, the better you are treated, to a degree: better rates on loans, no problems getting a job (all other things being equal), and so on. The opposite is true for bad scores.
This is one of the many ways we are corraled into greasing the gears of the economy, and it is a wasteland for cash-only operators (unless, I suppose, they have a huge amount of cash).