The real reason they oppose it (and other safety net things, like unemployment pay and health care that’s not tied to a job) is that they don’t want a mobile workforce that can easily quit or unionise if abused.

The power dynamics between employees and employers would shift dramatically if employees knew they could just stay home and still get a few $k to fall back on.

Heck, even the small stimulus checks during the pandemic had a huge effect like that that is still shaking out as increased union activity.