That average is the mean (we can tell because it roughly equals $1.76 trillion divided by 46.9 million borrowers).
The mean is notorious for being affected by outliers, that is, the few borrowers like doctors who owe tremendous sums. (As GP says, "the nightmare stories you hear are about the small, vocal minority")
If 90% of borrowers only owed $10k each, and the other 10% owed 210k each, the average would be $30k per borrower.
In fact, if 90% of borrowers only owed 1k each, and 10% owed 300k each, the average would still be over $30k.
Edit: According to the census, the median student loan debt is slightly under $20k, which certainly seems like an amount that people can pay off.
https://www.census.gov/library/stories/2021/08/student-debt-...