One thing that's been brought up in the past is that prior to this pandemic-driven WFH present (and probably is still true) is that secondary and satellite offices tend to not have limited openings or paths towards advancement. While a union might not be the best tool for the job, that seems like the sort of thing that organized employee opinion can try to influence. Maybe a lot of workers want to live and work in Austin, and management needs to invest more in the satellite office there, allow more career development opportunities, etc. This industry often seems to led by hidebound opinions that the rank-and-file often disagrees with. Fixation on Bay Area HQs, along with rejection of WFH and obsession with open offices, are examples of such policies which are seemingly only changed by something drastic as the threat of unionization- or more realistically- a worldwide pandemic.