First, even if you find a lawyer to take it on contingency, there are quite a few hard costs that are still out of pocket. Postage, document prep fees, travel expenses for depositions, expert witnesses, etc. It can literally be thousands of dollars.
Second, if your state does not allow for punitive damages for this type of violation, you need to prove damages. It is hard to quantify what the economic damage is of a credit denial or difficulty finding a lender is, and thus they will tie you and your lawyer’s time up with arguing this, even if they concede they erred.
Third, there is a serious time commitment to make in a lawsuit. Interviews, timely filings, certified mailings, depositions, etc. Easily tens of hours possibly hundreds.
Now, the type of person who can afford the time and expense of doing these things is generally also the type of person who can ignore a small hit to their credit score or a higher interest loan. Thus, these types of suits are not commonplace.
That said, I know someone who did this and was successful in getting a settlement.