Bypassing the gatekeepers
One reason to be in favor of basic income across the board is the issue of hiring bias.
There are jobs out there for many people, especially those in a reasonably affluent area who have the advantage of a formal education. But those jobs don’t always go to the most qualified applicants. Racism, ageism, sexism, religious prejudice -- these may be illegal in the hiring process, but they are still alive and well. Transphobia and appearance bias aren’t formally illegal in many places, but they affect the process as well. It’s something we brush off in Hollywood (Carrie Fisher has been outspoken about how hard it is to get acting jobs for women over 35, Gillian Anderson revealed that she was offered half as much for a role as her male co-star, and #OscarsSoWhite has highlighted the rampant racism issues), but it’s no more ethical there than it is in teaching, tech, publishing, finance, or anywhere else.
Ask any man in tech over 40 whether his age has been a concern while job-hunting. Ask anybody with a non-Anglicized name whether they’ve felt it impact their prospects. Ask any person of color whether things have suddenly cooled toward them after the first in-person interview. In many cases, as with trans individuals, the statistics speak for themselves -- systemic hiring bias exists, impacting some demographics to an enormous degree. This, in turn, affects their prosperity and the course of their lives, and it can enhance the poverty trap for those coming from a lower-class background. It leads to homelessness, ill health, and desperation.
Basic income would make survival much less dependent on the biases held by the gatekeepers of employment. Until we can achieve actual equality for oppressed groups, a minimum standard of living would allow them to secure their basic human needs without worrying about whether they were too black, or too old, or too foreign, or too non-conforming to pass the unwritten and unspoken tests for employment. This alone would bring our society closer to fairness and justice.