The banks have a profit motive for assessing credit risk accurately. They have a clear incentive to not underestimate prospective borrowers' credit risk (or th

The banks have a profit motive for assessing credit risk accurately. They have a clear incentive to not underestimate prospective borrowers' credit risk (or they'll lose more in defaults than they gain in interest), but the only incentive to not overestimate someone's credit risk is that someone else might offer a loan on better terms. Even if they are aware of flaws in their assessment process that overestimate a borrower's risk, they probably feel safe in the knowledge that everyone else is using that same process and will overestimate risk in the same way. A more accurate credit assessor could profit from this situation ("get your credit reports from us, and you can undercut lenders who rely on the big three"), but the barrier to entry is rather high.