Fair Isaac says that all of the top 50 U.S. financial institutions and the 25 largest credit card and auto lenders use its scores.

A group of Silicon Valley start-ups, including Social Finance Inc., Avant Inc., Affirm Inc. and Earnest Inc., is challenging FICO’s supremacy by arguing that bespoke scores based on data including borrowersincome and cash flow after expenses can better predict credit performance.

Part of the reason why FICO score are used as often as they are is that the information is fairly easy to come by.

FICO scores can be obtained from data providers without any effort from applicants.

The largest lenders are perpetuating the prevalence of FICO scores by giving their customers a regular glimpse at how they measure up in Fair Isaac’s eyes.

Banks, including Citigroup Inc. and Ally Financial Inc., and credit-card companies, including American Express Co and Discover Financial Services, disclose the FICO score of their customers on their account statements or websites.

Payoff Inc., which makes personal loans, announced in December that it was giving anyone who took a loan out from the company free monthly access to their FICO score.