"Letters of recommendation from teachers, school counselors and other sources can help college admissions officers get a more complete picture of applicants.
For instance, at the University of Wisconsin—Madison, a large public institution, admissions officers aren’t able to interview undergraduate applicants, says Bobbie Jean S. Huerth, assistant director of application evaluation and training at the university. So letters of recommendation are one of the few ways to learn about prospective students beyond their grades and test scores. …
… Obtaining high-quality letters of recommendation usually can’t happen overnight – it’s a process that takes time and advance planning. Here’s everything high school students need to know about asking for letters of recommendation for college applications." …
https://www.usnews.com/education/best-colleges/articles/letter-of-recommendation-for-college