Credit score is independent of income level. The score we use in our insurance risk modeling doesn't care about the amount of money you earn. There is a lot of actuarial papers just demonstrating this. Credit score is often though of something reflecting wealth. It is not the case. It is a score that reflects the likelyness of you defaulting on future obligations.
What parent is saying is that if you have a high income level, it's not the end of the world to pay cash for everything, so you can live with a bad credit score.
You might have to buy a beater while you save for a nice car, but if your income is low the equivalent option is taking the bus.
