So a non-populist politician implements an "effective" UBI policy, but since it's only effective for a short amount of time because things change and people realize later that it's not as fair/effective as they thought... or else you can only pass a compromise bill and it's really not effective at all, but you're told it will be (assuming you keep voting for X!).
I mean, why should everyone get the same amount? Or why should the percentage difference between my UBI this other groups be different by X amount?
Suddenly the UBI is just a new way to target voting blocks with promises of adjustments in their favor... essentially like how the tax code is used politically.
The only way to implement UBI effectively is to implement it a way where it can't be used as a populist political tool ever, which I think is impossible.
The most messed up thing I find about UBI is that it's the solution put forth by companies which are actively avoiding paying taxes through loopholes and havens.
Rather than someone like Zuckerberg thinking "Hmm... maybe I could help impoverished people by spreading my wealth to my employees more evenly and by paying my fair share in corporate/personal taxes to the local/state/federal govt?"
Instead they say "I deserve billions of dollars in personal wealth and to stay competitive (despite my effective monopoly) I must utilize every tax loophole possible and it's up to the government to find some other way to find the revenue to keep my users/employees at a living wage."
[0] https://en.wikipedia.org/wiki/Cura_Annonae