> Isn't it supposed to be a minimum base level of support? Why do we keep moving the goal posts?

Ultimately, the whole point of UBI is to head off political objections to automating away most jobs, so the tech barons can pursue the technology to do that unimpeded (at least until it's too late). "Minimum base level of support" is basically the Terrafoam welfare warehouses from Manna (https://marshallbrain.com/manna).